NAME

Muldis::D::Dialect::HDMD_Perl6_STD - How to format Perl 6 Hosted Data Muldis D

VERSION

This document is Muldis::D::Dialect::HDMD_Perl6_STD version 0.148.1.

PREFACE

This document is part of the Muldis D language specification, whose root document is Muldis::D; you should read that root document before you read this one, which provides subservient details.

DESCRIPTION

This document outlines the grammar of the Hosted Data Muldis D standard dialect named HDMD_Perl6_STD. The fully-qualified name of this Muldis D standard dialect is [ 'Muldis_D', 'http://muldis.com', '0.148.1', 'HDMD_Perl6_STD' ].

The HDMD_Perl6_STD dialect is defined to be hosted in Perl 6, and is composed of just|mainly core Perl 6 types. This dialect is optimized for Perl 6 specifically, and doesn't try to match the version for Perl 5; you *will* have to reformat any Perl Hosted Data Muldis D when migrating between Perl 5 and Perl 6, same as with your ordinary Perl code.

This dialect is designed to exactly match the structure of a possible concrete syntax tree, comprised of native Perl 6 scalar and collection typed values, resulting from parsing code written in the Muldis D dialect PTMD_STD using Perl 6. This dialect exists as a convenience to Perl 6 programmers that want to generate or introspect Muldis D code by saving them the difficulty and overhead of escaping and stitching plain text code; it is expected that a Muldis D implementation written in Perl 6 will natively accept input in both the PTMD_STD and HDMD_Perl6_STD dialects. Furthermore, the HDMD_Perl6_STD dialect provides additional Muldis D syntax options to Perl 6 programmers besides what PTMD_STD would canonically parse into, such as the direct use of some Perl 6-only features.

Note that most of the details that the 2 dialects have in common are described just in the PTMD_STD file, for both dialects; this current file will mainly focus on the differences; you should read the Muldis::D::Dialect::PTMD_STD file before the current one, so to provide a context for better understanding it.

GENERAL STRUCTURE

A HDMD_Perl6_STD Muldis D code file is actually a Perl 6 code file that defines particular multi-dimensional Perl data structures which resemble possible concrete syntax trees (CSTs) from parsing PTMD_STD Muldis D code. Each component of a CST is called a node or node element, and roughly corresponds to a capture by the PTMD_STD parser. A node is typically represened as a Perl Seq|Array, but could alternately be a Perl scalar or something else, and so HDMD_Perl6_STD Muldis D code is typically a tree of Perl structures, called node trees, with Perl Seq|Array as the central nodes and Perl scalars as the leaf nodes. Often HDMD_Perl6_STD code is embedded or constructed in one or more files of a larger Perl 5 program that does more than define this code, such as various non-database-related tasks. A node tree is just composed using basic Perl data types, and there are no Muldis D node-specific Perl classes or objects required for doing this.

Note that Perl undefined values are not allowed anywhere in a node in the general case; you must use only defined values instead. This documentation also assumes that only defined values are used, and that supplying a Perl undef will result in an error. The few exceptions to this rule are explicitly stated.

The grammar in this file is informal and consists just of written descriptions of how each kind of node must be composed and how to interpret such Perl data structures as Muldis D code. Every named grammar node is a Perl Seq|Array unless otherwise stated, and every grammar element is a Seq|Array element; the first node element is the Seq|Array element at index zero, and so on.

The root grammar node for the entire dialect is Muldis_D.

START

A Muldis_D node has 2 ordered elements where the first element is a language_name node and the second element is either a value node or a depot node.

See the pod sections in this file named "LANGUAGE NAME", "VALUE LITERALS AND SELECTORS", and "DEPOT SPECIFICATION", for more details about the aforementioned tokens/nodes.

When Muldis D is being compiled and invoked piecemeal, such as because the Muldis D implementing virtual machine (VM) is attached to an interactive user terminal, or the VM is embedded in a host language where code in the host language invokes Muldis D code at various times, many value may be fed to the VM directly for inter-language exchange, and not every one would then have its own language_name. Usually a language_name would be supplied to the Muldis D VM just once as a VM configuration step, which provides a context for further interaction with the VM that just involves Muldis D code that isn't itself qualified with a language_name.

LANGUAGE NAME

As per the VERSIONING pod section of Muldis::D, code written in Muldis D must start by declaring the fully-qualified Muldis D language name it is written in. The HDMD_Perl6_STD dialect formats this name as a language_name node having 5 ordered elements:

ln_base_name

This is the Muldis D language base name; it is simply the Perl Str value Muldis_D.

ln_base_authority

This is the base authority; it is a Perl Str formatted as per a specific-context Name value literal, except that must be nonempty and it is expressly limited to using non-control characters in the ASCII repertoire; it is typically the Perl Str value http://muldis.com.

ln_base_version_number

This is the base version number; it is a Perl Str formatted as per ln_base_authority; it is typically a Perl Str value like 0.148.1.

ln_dialect

This is the dialect name; it is simply the Perl Str value HDMD_Perl6_STD.

ln_extensions

This is a set of chosen pragma/parser-config options, which is formatted similarly to a Tuple SCVL. The only 2 mandatory pragmas are catalog_abstraction_level (see the "CATALOG ABSTRACTION LEVELS" pod section) and op_char_repertoire (see "OPERATOR CHARACTER REPERTOIRE"). The only optional pragma is standard_syntax_extensions (see the "STANDARD SYNTAX EXTENSIONS" pod section). Other pragmas may be added later, which would likely be optional.

The value associated with the ln_extensions attribute named catalog_abstraction_level must be one of these 4 Perl Str values: the_floor, code_as_data, plain_rtn_inv, rtn_inv_alt_syn.

The value associated with the ln_extensions attribute named op_char_repertoire must be one of these 2 Perl character strings: basic, extended.

The value associated with the ln_extensions attribute named standard_syntax_extensions must be formatted similarly to a Set SCVL; each of the value's elements must be one of these 0 Perl Str values.

Examples:

    [ 'Muldis_D', 'http://muldis.com', '0.148.1', 'HDMD_Perl6_STD', {
        catalog_abstraction_level => 'rtn_inv_alt_syn',
        op_char_repertoire => 'extended'
    } ]

    [ 'Muldis_D', 'http://muldis.com', '0.148.1', 'HDMD_Perl6_STD', {
        catalog_abstraction_level => 'rtn_inv_alt_syn',
        op_char_repertoire => 'extended',
        standard_syntax_extensions => Set.new()
    } ]

CATALOG ABSTRACTION LEVELS

The catalog_abstraction_level pragma determines with a broad granularity how large the effective Muldis D grammar is that a programmer may employ with their Muldis D code.

The catalog abstraction level of some Muldis D code is a measure of how much or how little that code would resemble the system catalog data that the code would parse into. The lower the abstraction level, the smaller and simpler the used Muldis D grammar is and the more like data structure literals it is; the higher the abstraction level, the larger and more complicated the Muldis D grammar is and the more like general-purpose-language typical code it is.

There are currently 4 specified catalog abstraction levels, which when arranged from lowest to highest amount of abstraction, are: the_floor, code_as_data, plain_rtn_inv, rtn_inv_alt_syn. Every abstraction level has a proper superset of the grammar of every other abstraction level that is lower than itself, so for example any code that is valid code_as_data is also valid plain_rtn_inv, and so on.

the_floor

This abstraction level exists more as an academic exercise and is not intended to actually be used.

Examples:

    [
        [ 'Muldis_D', 'http://muldis.com', '0.148.1', 'HDMD_Perl6_STD', {
            catalog_abstraction_level => 'the_floor',
            op_char_repertoire => 'basic'
        } ],
        :List[3,
           :List[
              :List[1,:List[102,111,111,100]],
              :List[1,:List[113,116,121]],
           ],
           :List[
              :List[
                 :List[4,
                    :List[
                       :List[1,:List[115,121,115]],
                       :List[1,:List[115,116,100]],
                       :List[1,:List[67,111,114,101]],
                       :List[1,:List[84,121,112,101]],
                       :List[1,:List[84,101,120,116]],
                    ],
                    :List[1,:List[110,102,100,95,99,111,100,101,115]],
                    :List[2,
                       :List[:List[1,:List[]]],
                       :List[:List[1,:List[67,97,114,114,111,116,115]]]
                    ]
                 ],
                 100
              ],
              :List[
                 :List[4,
                    :List[
                       :List[1,:List[115,121,115]],
                       :List[1,:List[115,116,100]],
                       :List[1,:List[67,111,114,101]],
                       :List[1,:List[84,121,112,101]],
                       :List[1,:List[84,101,120,116]],
                    ],
                    :List[1,:List[110,102,100,95,99,111,100,101,115]],
                    :List[2,
                       :List[:List[1,:List[]]],
                       :List[:List[1,:List[75,105,119,105,115]]]
                    ]
                 ],
                 30
              ]
           ]
        ]
    ]

code_as_data

This abstraction level is the best one for when you want to write code in exactly the same form as it would take in the system catalog.

Code written to the code_as_data level can employ all of the language grammar constructs described in these main pod sections: "VALUE LITERALS AND SELECTORS", "OPAQUE VALUE LITERALS", "COLLECTION VALUE SELECTORS".

Examples:

    [
        [ 'Muldis_D', 'http://muldis.com', '0.148.1', 'HDMD_Perl6_STD', {
            catalog_abstraction_level => 'code_as_data',
            op_char_repertoire => 'basic'
        } ],
        '@' => Set.new(
            { food => 'Carrots', qty => 100 },
            { food => 'Kiwis', qty => 30 }
        )
    ]

    [
       [ 'Muldis_D', 'http://muldis.com', '0.148.1', 'HDMD_Perl6_STD', {
          catalog_abstraction_level => 'code_as_data',
          op_char_repertoire => 'basic'
       } ],
       [ 'depot', :depot-catalog[ 'Database', 'Depot', {
          functions => '@' => Set.new(
             {
                name => :Name<cube>,
                material => [ '%', 'Function', {
                   result_type => :PNSQNameChain<Int>,
                   params => [ '@', 'NameTypeMap', Set.new(
                      { name => :Name<topic>, type => :PNSQNameChain<Int> }
                   ) ],
                   expr => [ 'Database', 'ExprNodeSet', {
                      sca_val_exprs => '@' => Set.new(
                         { name => :Name<INT_3>, value => 3 }
                      ),
                      func_invo_exprs => '@' => Set.new(
                         {
                            name => :Name(''),
                            function => :PNSQNameChain<Integer.power>,
                            args => [ '@', 'NameExprMap', [
                               {name=>:Name<radix>, expr=>:Name<topic>},
                               {name=>:Name<exponent>, expr=>:Name<INT_3>}
                            ] ]
                         }
                      )
                   } ]
                } ]
             }
          )
       } ] ]
    ]

plain_rtn_inv

This abstraction level is the lowest one that can be recommended for general use.

Code written to the plain_rtn_inv level can employ all of the language grammar constructs that code_as_data can, plus all of those described in these main pod sections: "MATERIAL SPECIFICATION", "GENERIC VALUE EXPRESSIONS", "GENERIC PROCEDURE STATEMENTS".

Examples:

    [
        [ 'Muldis_D', 'http://muldis.com', '0.148.1', 'HDMD_Perl6_STD', {
            catalog_abstraction_level => 'plain_rtn_inv',
            op_char_repertoire => 'basic'
        } ],
        [ 'depot', :depot-catalog[
            [ 'function', 'cube', [ 'Int', { topic => 'Int' } ] => [
                [ 'func-invo', 'Integer.power',
                    { radix => :d<topic>, exponent => 3 } ]
            ] ]
        ] ]
    ]

DEPRECATED - rtn_inv_alt_syn

The rtn_inv_alt_syn catalog abstraction level as it currently exists is deprecated and will disappear in the near future. Other pending enhancements to the language in both the system catalog itself and in the plain_rtn_inv level will make the latter more capable and suitable by itself for normal use. A new highest level or 3 will probably appear in place of rtn_inv_alt_syn later for their still-unique useful features.

This abstraction level is the highest one and is the most recommended one for general use.

Code written to the rtn_inv_alt_syn level can employ all of the language grammar constructs that plain_rtn_inv can, plus all of those described in these main pod sections: "DEPRECATED - FUNCTION INVOCATION ALTERNATE SYNTAX EXPRESSIONS", "DEPRECATED - PROCEDURE INVOCATION ALTERNATE SYNTAX STATEMENTS".

Examples:

    [
        [ 'Muldis_D', 'http://muldis.com', '0.148.1', 'HDMD_Perl6_STD', {
            catalog_abstraction_level => 'rtn_inv_alt_syn',
            op_char_repertoire => 'basic'
        } ],
        [ 'depot', :depot-catalog[
            [ 'function', 'cube', [ 'Int', { topic => 'Int' } ] => [
                [ 'i-op', 'exp', [ :d<topic>, 3 ] ]
            ] ]
        ] ]
    ]

OPERATOR CHARACTER REPERTOIRE

The op_char_repertoire pragma determines primarily whether or not the various routine invocation alternate syntaxes, herein called operators, may be composed of only ASCII characters or also other Unicode characters, and this pragma determines secondarily whether or not a few special value literals (effectively nullary operators) composed of non-ASCII Unicode characters may exist.

There are currently 2 specified operator character repertoires: basic, extended. The latter is a proper superset of the former.

Specifying the op_char_repertoire pragma in a language_name node is mandatory, since there is no obviously best setting to use implicitly when one isn't specified.

basic

The basic operator character repertoire is the smallest one, and it only supports writing the proper subset of defined operator invocations and special value literals that are composed of just 7-bit ASCII characters. This repertoire can be recommended for general use, especially since code written to it should be the most universally portable as-is (with respect to operator character repertoires), including full support even by minimal Muldis D implementations and older text editors.

extended

The extended operator character repertoire is the largest one, and it supports the entire set of defined operator invocations and special value literals, many of which are composed of Unicode characters outside the 7-bit ASCII repertoire. This is the most recommended repertoire for general use, assuming that all the Muldis D implementations and source code text editors you want to use support it.

STANDARD SYNTAX EXTENSIONS

The standard_syntax_extensions pragma declares which optional portions of the Muldis D grammar a programmer may employ with their Muldis D code.

There are currently no specified standard syntax extensions. These are all mutually independent and any or all may be used at once.

While each standard syntax extension is closely related to a Muldis D language extension, you can use the latter's types and routines without declaring the former; you only declare you are using a standard syntax extension if you want the Muldis D parser to recognize special syntax specific to those types and routines, and otherwise you just use them using the generic syntax provided for all types and routines.

The standard_syntax_extensions pragma is generally orthogonal to the catalog_abstraction_level pragma, so you can combine any value of the latter with any value-list of the former. However, in practice all standard syntax extensions will have no effect when the catalog abstraction level is the_floor, and some of their features may only take effect when the catalog abstraction level is rtn_inv_alt_syn, as is appropriate.

Specifying the standard_syntax_extensions pragma in a language_name node is optional, and when omitted it defaults to the empty set, meaning no extensions may be used.

VALUE LITERALS AND SELECTORS

A value node is a Muldis D value literal, which is a common special case of a Muldis D value selector.

There are 23 main varieties of value node, each of which is a named node kind of its own: Singleton, Bool, Order, RoundMeth, Int, Rat, Blob, Text, Name, NameChain, PNSQNameChain, RatRoundRule, Scalar, Tuple, Database, Relation, Set, Maybe, Array, Bag, [S|M]PInterval, List.

Fundamentally, the various Muldis D scalar and collection types are represented by their equivalent Perl native scalar and collection types. But since Muldis D is more strongly typed, or at least differently typed, than Perl, each value node is represented by a Perl Seq|Array, whose elements include both the payload Perl literal plus explicit metadata for how to interpret that Perl literal for mapping to Muldis D.

Value Literal Common Elements

Every value node is either a GCVL (generic context value literal) or a SCVL (specific context value literal).

Every GCVL has 1-3 ordered elements:

value_kind

This is a Perl Str value of the format <[A..Z]> <[ a..z A..Z ]>+ | '$'|'%'|'@'; it identifies the data type of the value literal in broad terms and is the only external metadata of value_payload generally necessary to interpret the latter; what grammars are valid for value_payload depend just on value_kind.

Between the various kinds of value node, these 42 values are allowed for value_kind: Singleton, Bool, Order, RoundMeth, [|NN|P]Int, [|NN|P]Rat, [|Octet]Blob, Text, Name, [|PNSQ]NameChain, RatRoundRule, [|DH]Scalar|$, [|DH]Tuple|%, Database, [|DH]Relation|@, [|DH]Set, [|DH][Maybe|Just], [|DH]Array, [|DH]Bag, [|DH][S|M]PInterval, List.

For just some data types, the value_kind may be omitted; see below.

type_name

Only when the value node has 3 elements: This is a Muldis D data type name, for example sys.std.Core.Type.Int; it identifies a specific subtype of the generic type denoted by value_kind, and serves as an assertion that the Muldis D value denoted by value_payload is a member of the named subtype. Its format is a PNSQNameChain_payload node. Iff value_kind is [|DH]Scalar then type_name is mandatory; otherwise, type_name is optional for all value, except that type_name must be omitted when value_kind is one of the 3 [Singleton, Bool, Order]; this isn't because those 3 types can't be subtyped, but because in practice doing so isn't useful.

value_payload

This is mandatory for all value. Format varies with value_kind.

A Perl Pair may alternately be used to represent a GCVL iff that node has exactly 2 elements (value_kind and value_payload); in that case, the value_kind is stored in that Pair's key, and the value_payload is stored in the Pair's value.

For some data types, a GCVL may alternately be just its payload for the sake of brevity. If any Perl value of one of the following types is encountered where a GCVL node is expected, then it is interpreted as a full value node as follows:

    Muldis D   <- Perl 6
    ----------------------------
    -Inf       <- -Inf
    Inf        <- Inf|+Inf
    Bool       <- Bool
    Order      <- Order
    Int        <- Int
    Rat        <- FatRat|Rat|Num
    Blob       <- Blob
    Text       <- Str
    SPInterval <- Range
    TAIInstant <- Instant  # TODO: UPDATE THIS! #
    TAIDuration <- Duration  # TODO: UPDATE THIS! #

The above details are subject to revision regarding when a Perl object might claim to do multiple type interfaces.

For GCVL and SCVL examples, see the subsequent documentation sections.

OPAQUE VALUE LITERALS

Singleton Literals

A Singleton node represents a value of any of the singleton scalar types that sys.std.Core.Type.Cat.Singleton is a union over. The payload must be one of these 2 special named Perl values: -Inf, Inf|+Inf.

Examples:

    :Singleton(-Inf)

    Inf

Boolean Literals

A Bool node represents a logical boolean value. It is interpreted as a Muldis D sys.std.Core.Type.Bool value as follows: The payload must be a Perl Bool, and so Bool::False and Bool::True are mapped directly.

Examples:

    :Bool(Bool::True)

    Bool::False

Order-Determination Literals

An Order node represents an order-determination. It is interpreted as a Muldis D sys.std.Core.Type.Cat.Order value as follows: The payload must be a Perl Order, and so Order::Less and Order::Same and Order::More are mapped directly.

Examples:

    :Order(Order::Same)

    Order::More

Rounding Method Literals

A RoundMeth node represents a rounding method. It is interpreted as a Muldis D sys.std.Core.Type.Cat.RoundMeth value by directly mapping the payload. The payload must be a Perl Str having one of the 9 values Down, Up, ToZero, ToInf, HalfDown, HalfUp, HalfToZero, HalfToInf, HalfEven.

Examples:

    :RoundMeth<HalfUp>

    :RoundMeth<ToZero>

General Purpose Integer Numeric Literals

An Int node represents an integer numeric value. It is interpreted as a Muldis D sys.std.Core.Type.Int value as follows: The payload must be a Perl Int, which is mapped directly.

Examples:

    :Int(0b11001001) # binary #

    0o0 # octal #

    0o644 # octal #

    -34 # decimal #

    42 # decimal #

    0xDEADBEEF # hexadecimal #

    :36<-HELLOWORLD> # base-36 #

    :4<301> # base-4 #

    :12<A09B> # base-12 #

General Purpose Rational Numeric Literals

A Rat node represents a rational numeric value. It is interpreted as a Muldis D sys.std.Core.Type.Rat value as follows: The payload must be a Perl FatRat|Rat|Num|Int, which is mapped directly.

Examples:

    :Rat(-0b1.1)

    -1.5 # same val as prev #

    3.14159

    :11<0.0>

    0xDEADBEEF.FACE

    :36<0.000AZE>

    :Rat(:7<500001>/:7<1000>)

    :12<A09B>/:12<A>

    :Rat(0b1011101101 * 0b10 ** -0b11011)

    45207196 * 10 ** 37

    1/43

    314159 * 10 ** -5

General Purpose Binary String Literals

A Blob node represents a general purpose bit string. It is interpreted as a Muldis D sys.std.Core.Type.Blob value as follows: The payload must be a Perl Blob, which is mapped directly.

Examples:

    :Blob(:2{00101110100010}) # binary #

    :4{}

    :16{A705E} # hexadecimal #

    :8{523504376}

General Purpose Character String Literals

A Text node represents a general purpose character string. It is interpreted as a Muldis D sys.std.Core.Type.Text value by directly mapping the payload. The payload must be a Perl Str.

Examples:

    :Text<Ceres>

    'サンプル'

    ''

    'Perl'

    "\c[LATIN SMALL LETTER OU]\x[263A]\c[65]"

DBMS Entity Name Literals

A Name node represents a canonical short name for any kind of DBMS entity when declaring it; it is a character string type, that is disjoint from Text. It is interpreted as a Muldis D sys.std.Core.Type.Cat.Name value by directly mapping the payload. The payload must be a Perl Str.

A NameChain node represents a canonical long name for invoking a DBMS entity in some contexts; it is conceptually a sequence of entity short names. Its payload is a Perl Seq|Array value or Str value. This node is interpreted as a Muldis D sys.std.Core.Type.Cat.NameChain value as follows:

• If the payload is a Seq|Array, then every element must be a valid payload for a Name node (that is, any Perl character string). Each element of the payload, in order, defines an element of the array possrep's attribute of a NameChain.

• If the payload is a Str, then it must be formatted as a catenation (using period (.) separators) of at least 1 part, where each part can not have any literal period (.) characters (if you want literal periods then you can only use the Seq|Array payload format to express it). The Str format of payload is interpreted by splitting it on the separators into the Seq|Array format, then processed as per the latter. A zero part chain can only be expressed with the Seq|Array payload format; an empty string Str format will be interpreted as having a single element that is the empty string.

Fundamentally a PNSQNameChain node is exactly the same as a NameChain node in format and interpretation, with the primary difference being that it may only define NameChain values that are also values of the proper subtype sys.std.Core.Type.Cat.PNSQNameChain, all of which are nonempty chains. Now that distinction alone wouldn't be enough rationale to have these 2 distinct node kinds, and so the secondary difference between the 2 provides that rationale; the PNSQNameChain node supports a number of chain value shorthands while the NameChain node supports none.

A PNSQNameChain node is interpreted the same as a NameChain node except for the extra restrictions and shorthands.

Examples:

    :Name<login_pass>

    :Name('First Name')

    :NameChain['gene','sorted_person_name']

    :NameChain('stats.samples by order')

    :NameChain[]

    :PNSQNameChain['fed','data','the_db','gene','sorted_person_names']

    :PNSQNameChain('fed.data.the_db.stats.samples by order')

Rational Rounding Rule Literals

A RatRoundRule node represents a rational rounding rule. It is interpreted as a Muldis D sys.std.Core.Type.Cat.RatRoundRule value whose attributes are defined by the RatRoundRule_payload. A RatRoundRule_payload must be a Perl Seq|Array with 3 elements, which correspond in order to the 3 attributes: radix (a PInt2_N), min_exp (an Int), and round_meth (a RoundMeth). Each of radix and min_exp must qualify as a valid Int_payload, and round_meth must qualify as a valid RoundMeth_payload.

Examples:

    :RatRoundRule[10,-2,'HalfEven']

    :RatRoundRule[2,-7,'ToZero']

COLLECTION VALUE SELECTORS

Note that, with each of the main value selector nodes documented in this main POD section, any occurrences of child expr nodes should be read as being value nodes instead in contexts where instances of the main nodes are being composed beneath value nodes. That is, any expr node options beyond what value options exist are only valid within a depot node.

Scalar Selectors

A Scalar node represents a literal or selector invocation for a not-Int|String scalar subtype value. It is interpreted as a Muldis D sys.std.Core.Type.Scalar subtype value whose declared type is specified by the node's (mandatory for Scalar) type_name element and whose attributes are defined by the payload. If the payload is a Perl Pair, then its key and value, respectively, are designated possrep name and possrep attrs; if the payload is not a Perl Pair, then it is interpreted as if it was just the possrep attrs, and the possrep name was the empty string. The possrep name and possrep attrs must be as per the payload of a Name and Tuple node, respectively. The possrep attrs is interpreted specifically as attributes of the declared type's possrep which is specified by the possrep name. Each key+value pair of the possrep attrs defines a named possrep attribute of the new scalar; the pair's key and value are, respectively, a Perl Str that specifies the possrep attribute name, and an expr node that specifies the possrep attribute value.

Examples:

    [ 'Scalar', 'Name', { '' => 'the_thing' } ]

    [ '$', 'Rat', float => {
        mantissa => 45207196,
        radix    => 10,
        exponent => 37,
    } ]

    [ '$', 'fed.lib.the_db.UTCDateTime', datetime => {
        year   => 2003,
        month  => 10,
        day    => 26,
        hour   => 1,
        minute => 30,
        second => 0.0,
    } ]

    [ '$', 'fed.lib.the_db.WeekDay', name => {
        '' => 'monday',
    } ]

    [ '$', 'fed.lib.the_db.WeekDay', number => {
        '' => 5,
    } ]

Tuple Selectors

A Tuple node represents a literal or selector invocation for a tuple value. It is interpreted as a Muldis D sys.std.Core.Type.Tuple value whose attributes are defined by the payload. The payload must be a Perl Mapping|Hash. Each key+value pair of the payload defines a named attribute of the new tuple; the pair's key and value are, respectively, a Perl Str that specifies the attribute name, and an expr node that specifies the attribute value.

Examples:

    :Tuple{}

    [ '%', 'type.tuple_from.var.fed.data.the_db.account.users', {
        login_name => 'hartmark',
        login_pass => 'letmein',
        is_special => Bool::True,
    } ]

    '%' => {
        name => 'Michelle',
        age  => 17,
    }

Database Selectors

A Database node represents a literal or selector invocation for a 'database' value. It is interpreted as a Muldis D sys.std.Core.Type.Database value whose attributes are defined by the payload. The payload must be a Perl Mapping|Hash. Each key+value pair of the payload defines a named attribute of the new 'database'; the pair's key and value are, respectively, a Perl Str that specifies the attribute name, and an expr node that specifies the attribute value, which must be represent a relation value.

Relation Selectors

A Relation node represents a literal or selector invocation for a relation value. It is interpreted as a Muldis D sys.std.Core.Type.Relation value whose attributes and tuples are defined by the payload, which is interpreted as follows:

• Iff the payload is a Perl Set|KeySet with zero elements, then it defines the only relation value having zero attributes and zero tuples.

• Iff the payload is a Perl Set|KeySet with at least one element, and every element is a Perl Str (as per a valid payload for a Name node), then it defines the attribute names of a relation having zero tuples.

• Iff the payload is a Perl Set|KeySet with at least one element, and every element is a Perl Mapping|Hash (as per a valid payload for a Tuple node), then each element of the payload defines a tuple of the new relation; every tuple-defining element of the payload must be of the same degree and have the same attribute names as its sibling elements; these are the degree and attribute names of the relation as a whole, which is its heading for the current purposes.

• Iff the payload is a Perl Pair, then: The new relation value's attribute names are defined by the payload's key, which is a Perl Seq|Array of Str (each as per a Name node payload), and the relation body's tuples' attribute values are defined by the payload's value, which is a Perl Set|KeySet of Seq|Array of tuple attribute value defining nodes. This format is meant to be the most compact of the generic relation payload formats, as the attribute names only appear once for the relation rather than repeating for each tuple. As a trade-off, the attribute values per tuple from the payload value must appear in the same order as their corresponding attribute names appear in the payload key, as the names and values in the relation literal are matched up by ordinal position here.

Examples TODO: What is the actual syntax for the P6 Set type?:

    :Relation( Set.new() )  # zero attrs + zero tuples #

    '@' => Set.new(<x y z>)  # 3 attrs + zero tuples #

    '@' => Set.new( {} )  # zero attrs + 1 tuple #

    '@' => Set.new(
        {
            login_name => 'hartmark',
            login_pass => 'letmein',
            is_special => Bool::True,
        },
    )  # 3 attrs + 1 tuple #

    [ '@', 'fed.lib.the_db.gene.Person', <name age> => Set.new(
        [ 'Michelle', 17 ],
    ) ]  # 2 attrs + 1 tuple #

Set Selectors

A Set node represents a literal or selector invocation for a set value. It is interpreted as a Muldis D sys.std.Core.Type.Set value whose elements are defined by the payload. The payload must be a Perl Set|KeySet. Each element of the payload defines a unary tuple of the new set; each element is an expr node that defines the value attribute of the tuple.

Examples TODO: What is the actual syntax for the P6 Set type?:

    [ 'Set', 'fed.lib.the_db.account.Country_Names', Set.new(
        'Canada',
        'Spain',
        'Jordan',
        'Thailand',
    ) ]

    :Set( Set.new(
        3,
        16,
        85,
    ) )

Maybe Selectors

A Maybe node represents a literal or selector invocation for a maybe value. It is interpreted as a Muldis D sys.std.Core.Type.Maybe value. If the node payload is missing or undefined, then the node is interpreted as the special value Maybe:Nothing, aka Nothing, which is the only Maybe value with zero elements. If the node payload is defined then the node is interpreted as a Just whose element is defined by the payload. The payload is an expr node that defines the value attribute of the single tuple of the new 'single'.

Examples:

    :Maybe( 'I know this one!' )

    :Maybe()  # or how does Perl 6 make a Pair with undef/default value? #

Array Selectors

An Array node represents a literal or selector invocation for an array value. It is interpreted as a Muldis D sys.std.Core.Type.Array value whose elements are defined by the payload. The payload must be a Perl Seq|Array. Each element of the payload defines a binary tuple of the new sequence; the element value is an expr node that defines the value attribute of the tuple, and the element index is used as the index attribute of the tuple.

Examples:

    :Array[
        'Alphonse',
        'Edward',
        'Winry',
    ]

    [ 'Array', 'fed.lib.the_db.stats.Samples_By_Order', [
        57,
        45,
        63,
        61,
    ] ]

Bag Selectors

A Bag node represents a literal or selector invocation for a bag value. It is interpreted as a Muldis D sys.std.Core.Type.Bag value whose elements are defined by the payload. The payload must be a Perl Bag|KeyBag|Set|KeySet value; the payload element keys are expr nodes corresponding to the value attribute of the new bag's tuples, and the payload element values are positive integers (or Bool::True, which counts as the number 1) corresponding to the count attribute; the payload element mapping is as you should expect.

Examples TODO: What is the actual syntax for the P6 Bag type?:

    [ 'Bag', 'fed.lib.the_db.inventory.Fruit', Bag.new(
        'Apple'  => 500,
        'Orange' => 300,
        'Banana' => 400,
    ) ]

    :Bag( Bag.new(
        'Foo',
        'Quux',
        'Foo',
        'Bar',
        'Baz',
        'Baz',
    ) )

Interval Selectors

An SPInterval node represents a literal or selector invocation for a single-piece interval value. It is interpreted as a Muldis D sys.std.Core.Type.SPInterval value whose attributes are defined by the payload. The node payload must be a Perl Range, which is mapped directly. Each of the min and max attributes/method-return-values of the Range is an expr node that defines the min and max attribute value, respectively, of the new single-piece interval. Each of the excludes_min and excludes_max of the Range maps directly with the single-piece interval.

A special shorthand for an SPInterval payload also exists, which is to help with the possibly common situation where an interval is a singleton, meaning the interval has exactly 1 value; the shorthand empowers that value to be specified just once rather than twice. Iff the payload is not a Perl Range, then the payload is treated as if it was instead the usual Perl Range, whose min and max are both identical to the actual payload and whose excludes_min and excludes_max are both Bool::False. For example, the payload 6 is shorthand for 6..6.

An MPInterval node represents a literal or selector invocation for a multi-piece interval value. It is interpreted as a Muldis D sys.std.Core.Type.MPInterval value whose elements are defined by the payload. The payload must be a Perl Set|KeySet. Each element of the payload must be a valid payload for an SPInterval node (that is, a Perl Range). Each element of the payload defines a 4-ary tuple, representing a single-piece interval, of the new multi-piece interval.

Examples TODO: What is the actual syntax for the P6 Set type?:

    :SPInterval(1..10)

    2.7..^9.3

    'a'^..'z'

    :UTCInstant[2002,12,6] ^..^ :UTCInstant[2002,12,20]

    :SPInterval<abc>  # 1 element #

    :MPInterval( Set.new() )  # zero elements #

    :MPInterval( Set.new(1..10) )  # 10 elements #

    :MPInterval( Set.new(1..3,6,8..9) )  # 6 elements #

    :MPInterval( Set.new(-Inf..3,14..21,29..Inf) )
        # all Int besides {4..13,22..28} #

Low Level List Selectors

A List node represents a literal or selector invocation for a low-level list value. It is interpreted as a Muldis D sys.std.Core.Type.Cat.List value whose elements are defined by the payload. The payload must be just a Perl Seq|Array. Each element of the payload defines an element of the new list, where the elements keep the same order.

Examples:

    # Nonstructure : Unicode abstract codepoints = 'Perl' #
    :List[80,101,114,109]

    # UCPString : Unicode abstract codepoints = 'Perl' #
    :List[1,:List[80,101,114,109]]

    # %:{} #
    :List[2,:List[],:List[]]

    # @:{} #
    :List[3,:List[],:List[]]

    # Set : {17,42,5} #
    :List[3,
        :List[:List[1,:List[118,97,108,117,101]]],
        :List[
            :List[17],
            :List[42],
            :List[5]
        ]
    ]

    # Nothing #
    :List[3,
        :List[:List[1,:List[118,97,108,117,101]]],
        :List[]
    ]

    # Text : 'Perl' #
    :List[4,
        # type name : 'sys.std.Core.Type.Text' #
        :List[
            :List[1,:List[115,121,115]],
            :List[1,:List[115,116,100]],
            :List[1,:List[67,111,114,101]],
            :List[1,:List[84,121,112,101]],
            :List[1,:List[84,101,120,116]],
        ],
        # possrep name : 'nfd_codes' #
        :List[1,:List[110,102,100,95,99,111,100,101,115]],
        # possrep attributes : %:{""=>"Perl"} #
        :List[2,
            :List[:List[1,:List[]]],
            :List[:List[1,:List[80,101,114,109]]]
        ]
    ]

DEPOT SPECIFICATION

A depot node has 2-3 ordered elements such that 3 elements means the depot has a normal-user-data database and 2 elements means it has just a (possibly empty) system catalog database: The first element is the Perl Str value depot. Iff the depot has 3 elements then the third element specifies the normal-user-data database; it is a Perl Pair whose key is the Perl Str value depot-data and whose value is a Database node. The second element specifies the system catalog database; it is a Perl Pair whose key is the Perl Str value depot-catalog and whose value is either a Database node or a Perl Seq|Array which is hereafter referred to as depot_catalog_payload. A depot_catalog_payload either has zero elements, designating an empty catalog, or all of its elements are Perl Seq|Array (in particular, none of its elements is the Perl Str value 'Database'), each of which is one of the following kinds of nodes: subdepot, named_material, self_local_dbvar_type.

A subdepot node has 3 ordered elements: The first element is the Perl Str value subdepot. The second element is a Name_payload, which is the declared name of the subdepot within the namespace defined by its parent subdepot (or depot). The third element is a depot_catalog_payload.

A self_local_dbvar_type node has 2 ordered elements: The first element is the Perl Str value self-local-dbvar-type. The second element is a PNSQNameChain_payload, which specifies what the normal-user-data database has as its declared data type.

Examples:

    # A completely empty depot that doesn't have a self-local dbvar. #
    [ 'depot', :depot-catalog[] ]

    # Empty depot with self-local dbvar with unrestricted allowed values. #
    [ 'depot',
        :depot-catalog[
            :self-local-dbvar-type<Database>
        ],
        :depot-data[ 'Database', {} ]
    ]

    # A depot having just one function and no dbvar. #
    [ 'depot', :depot-catalog[
        [ 'function', 'cube', [ 'Int', { topic => 'Int' } ] => [
            [ 'i-op', 'exp', [ :d<topic>, 3 ] ]
        ] ]
    ] ]

MATERIAL SPECIFICATION

A material node specifies a new material (routine or type) that lives in a depot or subdepot.

There are 13 main varieties of material node, each of which is a named node kind of its own: function, procedure, scalar_type, tuple_type, relation_type, domain_type, subset_type, mixin_type, key_constr, distrib_key_constr, subset_constr, distrib_subset_constr, stim_resp_rule.

Material Specification Common Elements

A material node has 2-3 ordered elements, such that a material that has 2 elements is an anon_material and a material with 3 elements is a named_material: The first element is material_kind. The last element is material_payload. Iff there are 3 elements then the middle element is material_declared_name.

material_kind

This is a Perl Str value of the format [<[ a..z ]>+] ** '-'; it identifies the kind of the material and is the only external metadata of material_payload generally necessary to interpret the latter; what grammars are valid for material_payload depend just on material_kind.

material_declared_name

This is the declared name of the material within the namespace defined by its subdepot (or depot). It is explicitly specified iff the material is a named_material

material_payload

This is mandatory for all material. It specifies the entire material sans its name. Format varies with material_kind.

For material examples, see the subsequent documentation sections.

Note that, for simplicity, the subsequent sections assume for now that named_material is the only valid option, and so the material_declared_name isn't optional, and the only way to embed a material in another is using a with_clause.

Function Specification

A function node specifies a new function that lives in a depot or subdepot. A function node has 3 ordered elements: The first element is one of these 8 Perl Str values: function, named-value, value-map, value-map-unary, value-filter, value-constraint, value-reduction, order-determination. The second element is a Name_payload, which is the function's declared name. The third element is a function_payload. A function_payload is a Perl Pair whose key and value are designated, in order, function_heading and function_body.

A function_heading is a Perl Seq|Array with 2-3 ordered elements. The first element is designated result_type and is mandatory. The second element is designated func_params and is mandatory. The third element is designated implements and is optional.

A result_type is a type_name which is a PNSQNameChain_payload.

A func_params is structurally a proper subset of an proc_params; every valid proc_params is also a structurally valid func_params except for any procedure_payload that has either a ::= element or a & element; in other words, a function has neither global nor subject-to-update parameters; it just has regular read-only parameters.

A function_body must be either the Perl character string ..., in which case it is an empty_routine_body, or it must be a Perl Seq|Array, having at least one element which is an expr, and each other element of said Perl Seq|Array must be either a with_clause or a named_expr.

Each of implements and with_clause of a function_payload is structurally identical to one of a procedure_payload.

Examples:

    [ 'function', 'cube', [ 'Int', { topic => 'Int' } ] => [
        [ 'i-op', 'exp', [ :d<topic>, 3 ] ]
    ] ]

Procedure Specification

A procedure node specifies a new procedure that lives in a depot or subdepot. A procedure node has 3 ordered elements: The first element is one of these 5 Perl Str values: procedure, system-service, transaction, recipe, updater. The second element is a Name_payload, which is the procedure's declared name. The third element is a procedure_payload. A procedure_payload is a Perl Pair whose key and value are designated, in order, procedure_heading and procedure_body.

Iff the procedure_heading is a Perl Seq|Array, then it has 1-2 ordered elements. The first element is designated proc_params and is mandatory. The second element is designated implements and is optional. Iff the procedure_heading is a Perl Mapping|Hash, then it is designated proc_params and there is no implements.

A proc_params is a Perl Mapping|Hash; it must have at least one element, meaning the procedure has one or more parameters; each hash element specifies one parameter, and for each hash element, the hash element's key and value, respectively, are designated param_name and param_details. Iff param_details is a Perl Seq|Array with at least two elements, and its first element is not a non-empty Perl Str value consisting of just the characters <[ a..z A..Z 0..9 _ - ]>, then the param_details is a param_multi_meta; otherwise, param_details is a param_single_meta.

Iff a parameter's param_details is a param_single_meta, then the latter must be either a PNSQNameChain_payload or a single-element array whose sole element is one of those; then the parameter is a ro_reg_param, its param_details is designated type_name, and it has no param_flag.

Iff a parameter's param_details is a param_multi_meta, then the latter's last element must be a PNSQNameChain_payload, and each of the param_details' other elements must be a distinct one of these 4 Perl Str values: &, ?, @, ::=. A param_multi_meta must have at least 1 of those 4 and at most 2 of them, and furthermore only certain permutations are allowed. A & may be used either alone or in combination with exactly one of the other 3; its presence means that the parameter is subject-to-update; its absence means the parameter is read-only; iff a & is used then it must be the first param_details element. The 3 of ?, @, ::= are mutually exclusive so a param_details may have at most one of them, either alone or with a &.

Iff a parameter's param_details is a param_multi_meta and it does not have a ::= element, then the parameter is a regular parameter. A regular parameter's last (PNSQNameChain_payload) element is designated type_name. Iff a regular parameter has a & element then the parameter is an upd_reg_param; otherwise it is a ro_reg_param. Iff a regular parameter has a ? then the parameter has an opt_param_flag. Iff a regular parameter has a @ then the parameter has a dispatch_param_flag.

Iff a parameter's param_details is a param_multi_meta and it does have a ::= element, then the parameter is a global parameter. A global parameter's last (PNSQNameChain_payload) element is designated global_var_name. Iff a global parameter has a & element then the parameter is an upd_global_param; otherwise it is a ro_global_param.

An implements must be either a PNSQNameChain_payload or a Perl Seq|Array having zero or more elements where every element is a PNSQNameChain_payload; each PNSQNameChain_payload names a virtual procedure which the current procedure is declaring that it implements.

A procedure_body must be either the Perl Str value ..., in which case it is an empty_routine_body, or it must be a Perl Seq|Array having zero or more elements where each element must be either a with_clause or a proc_var or a named_expr or a proc_stmt; zero elements means that the procedure is an unconditional no-op.

A with_clause is a Perl Pair whose key is the Perl Str value with and whose value is a material node.

A proc_var is a 3-element Perl Seq|Array whose first element is the Perl Str value var, whose second element is a Name_payload, and whose third element is a type_name which is a PNSQNameChain_payload.

Examples:

    [ 'procedure', 'print_curr_time', {} => [
        [ 'var', 'now', 'Instant' ],
        [ 'proc-invo', 'fetch_trans_instant', [ ['&',:d<now>] ] ],
        [ 'proc-invo', 'write_Text_line', [ [ 'i-op', '~', [
            'The current time is: ',
            [ 'func-invo', 'nlx.par.lib.utils.time_as_text',
                { time => :d<now> } ]
        ] ] ] ],
    ] ]

    [ 'recipe', 'count_heads', { count => ['&','NNInt'], search => 'Text',
            people => ['::=','fed.data.db1.people'] } => [
        :with[ 'value-filter', 'filt',
            [ 'Bool', { topic => 'Tuple', search => 'Text' } ]
            => [
                [ 'i-op', 'like', [ :acc<topic.name>,
                    [ 'i-op', '~', [ '%', :d<search>, '%' ] ] ] ]
            ]
        ],
        [ 'i-op', ':=', [ :d<count>, [ 'pre-op', '#, [
            [ 'i-op', 'where', [ :d<people>,
                ['curried-func', 'nlx.lib.filt', {search=>:d<search>}]
            ] ]
        ] ] ] ],
    ] ]

    [ 'updater', 'make_coprime', {a=>['&','NNInt'],b=>['&','NNInt']} => [
        :with[ 'function', 'gcd',
            [ 'NNInt', { a => 'NNInt', b => 'NNInt' } ]
            => [
                [ '??!!', [ 'i-op', '=', [ :d<b>, 0 ] ],
                    :d<a>,
                    [ 'func-invo', 'rtn', { a => :d<b>,
                        b => [ 'i-op', 'mod', [ :d<a>, :d<b>,
                            :RoundMeth<Down> ] ] } ]
                ]
            ]
        ],
        [ '::=', 'gcd', [ 'func-invo', 'nlx.lib.gcd',
            { a => :d<a>, b => :d<b> } ] ],
        [ 'i-op', ':=', [ :d<a>, [ 'i-op', 'div',
            [ :d<a>, :d<gcd>, :RoundMeth<Down> ] ] ] ],
        [ 'i-op', ':=', [ :d<b>, [ 'i-op', 'div',
            [ :d<b>, :d<gcd>, :RoundMeth<Down> ] ] ] ],
    ] ]

Scalar Type Specification

A scalar_type node specifies a new scalar type that lives in a depot or subdepot. A scalar_type node has 3 ordered elements: The first element is the Perl Str value scalar-type. The second element is a Name_payload, which is the scalar type's declared name. The third element is a scalar_type_payload.

TODO: The remaining description.

TODO: Examples.

Tuple Type Specification

A tuple_type node specifies a new tuple type that lives in a depot or subdepot. A tuple_type node has 3 ordered elements: The first element is one of these 2 Perl Str values: tuple-type, database-type. The second element is a Name_payload, which is the tuple type's declared name. The third element is a tuple_type_payload.

TODO: The remaining description.

Examples:

    # db schema with 3 relvars, 2 subset constrs, the 5 def separately #
    [ 'database-type', 'CD_DB', [
        [ 'attr', 'artists', 'nlx.lib.Artists' ],
        [ 'attr', 'cds'    , 'nlx.lib.CDs'     ],
        [ 'attr', 'tracks' , 'nlx.lib.Tracks'  ],
        :constraint<nlx.lib.sc_artist_has_cds>,
        :constraint<nlx.lib.sc_cd_has_tracks>,
    ] ]

    # relation type using tuple virtual-attr-map for case-insen key attr #
    # where primary text data is case-sensitive, case-preserving #
    [ 'relation-type', 'Locations', [
        :tuple-type<nlx.lib.Location>,
        :with[ 'tuple-type', 'Location', [
            [ 'attr', 'loc_name'   , 'Text' ],
            [ 'attr', 'loc_name_uc', 'Text' ],
            virtual-attr-map:{
                determinant-attrs => { loc_name => 'loc_name' },
                dependent-attrs   => { loc_name_uc => 'loc_name_uc' },
                map-function      => 'nlx.lib.uc_loc_name'
            },
            :with[ 'value-map-unary', 'uc_loc_name',
                [ 'Tuple', { topic => 'Tuple' } ]
                => [
                    [ '%', { loc_name_uc => [ 'func-invo', 'upper',
                        [ :acc<topic.loc_name> ] ] } ]
                ]
            ],
        ] ],
        :constraint<nlx.lib.sk_loc_name_uc>,
        :with['key-constraint', 'sk_loc_name_uc', 'loc_name_uc'],
    ] ]

    # db schema with 2 real relvars, 1 virtual relvar; all are updateable #
    # real products has attrs { product_id, name } #
    # real sales has attrs { product_id, qty } #
    # virtual combines has attrs { product_id, name, qty } #
    [ 'database-type', 'DB', [
        [ 'attr', 'products', 'nlx.lib.Products' ],
        [ 'attr', 'sales'   , 'nlx.lib.Sales'    ],
        [ 'attr', 'combines', 'nlx.lib.Combines' ],
        virtual-attr-map:{
            determinant-attrs => {products => 'products',sales => 'sales'},
            dependent-attrs   => { combines => 'combines' },
            map-function      => 'nlx.lib.combine_p_s',
            is-updateable     => Bool::True
        },
        :with[ 'value-map-unary', 'combine_p_s',
            [ 'Database', { topic => 'Database' } ]
            => [
                [ 'Database', { combines => [ 'i-op', 'join',
                    [ :acc<topic.products>, :acc<topic.sales> ] ] } ]
            ]
        ],
    ] ]

Relation Type Specification

A relation_type node specifies a new relation type that lives in a depot or subdepot. A relation_type node has 3 ordered elements: The first element is the Perl Str value relation-type. The second element is a Name_payload, which is the relation type's declared name. The third element is a relation_type_payload.

TODO: The remaining description.

Examples:

    [ 'relation-type', 'Artists', [
        :with[ 'tuple-type', 'Artist', [
            [ 'attr', 'artist_id'  , 'Int'  ],
            [ 'attr', 'artist_name', 'Text' ],
        ] ],
        :with[ 'primary-key', 'pk_artist_id', 'artist_id' ],
        :with[ 'key-constraint', 'sk_artist_name', 'artist_name' ],
        :tuple-type<nlx.lib.Artist>,
        :constraint<nlx.lib.pk_artist_id>,
        :constraint<nlx.lib.sk_artist_name>,
    ] ]

    [ 'relation-type', 'CDs', [
        :with[ 'tuple-type', 'CD', [
            [ 'attr', 'cd_id'    , 'Int'  ],
            [ 'attr', 'artist_id', 'Int'  ],
            [ 'attr', 'cd_title' , 'Text' ],
        ] ],
        :with[ 'primary-key', 'pk_cd_id', 'cd_id' ],
        :with[ 'key-constraint', 'sk_cd_title', 'cd_title' ],
        :tuple-type<nlx.lib.CD>,
        :constraint<nlx.lib.pk_cd_id>,
        :constraint<nlx.lib.sk_cd_title>,
    ] ]

Domain Type Specification

A domain_type node specifies a new domain type that lives in a depot or subdepot. A domain_type node has 3 ordered elements: The first element is the Perl Str value domain-type. The second element is a Name_payload, which is the domain type's declared name. The third element is a domain_type_payload.

TODO: The remaining description.

TODO: Examples.

Subset Type Specification

A subset_type node specifies a new subset type that lives in a depot or subdepot. A subset_type node has 3 ordered elements: The first element is the Perl Str value subset-type. The second element is a Name_payload, which is the subset type's declared name. The third element is a subset_type_payload.

TODO: The remaining description.

TODO: Examples.

Mixin Type Specification

A mixin_type node specifies a new mixin type that lives in a depot or subdepot. A mixin_type node has 3 ordered elements: The first element is the Perl Str value mixin-type. The second element is a Name_payload, which is the mixin type's declared name. The third element is a mixin_type_payload.

TODO: The remaining description.

TODO: Examples.

Key Constraint Specification

A key_constr node specifies a new unique key constraint or candidate key, for a relation type, that lives in a depot or subdepot. A key_constr node has 3 ordered elements: The first element is one of these 2 Perl Str values: key-constraint, primary-key. The second element is a Name_payload, which is the constraint's declared name. The third element is a key_constr_payload, which is just a Perl Set|KeySet of 0..N elements where each of said elements is a Name_payload, which is the name of an attribute that the key ranges over; alternately, a key_constr_payload may be just a Name_payload, which is equivalent to the Set|KeySet format with 1 element.

Examples:

    # at most one tuple allowed #
    [ 'key-constraint', 'maybe_one', Set.new() ]

    # relation type's artist_id attr is its primary key #
    [ 'primary-key', 'pk_artist_id', 'artist_id' ]

    # relation type has surrogate key over both name attrs #
    [ 'key-constraint', 'sk_name', Set.new( 'last_name', 'first_name' ) ]

Distributed Key Constraint Specification

TODO.

Subset Constraint Specification

A subset_constr node specifies a (non-distributed) subset constraint (foreign key constraint) over relation-valued attributes, for a tuple type, that lives in a depot or subdepot. A subset_constr node has 3 ordered elements: The first element is the Perl Str value subset-constraint. The second element is a Name_payload, which is the constraint's declared name. The third element is a subset_constr_payload.

TODO: The remaining description.

Examples:

    # relation foo must have exactly 1 tuple when bar has at least 1 #
    [ 'subset-constraint', 'sc_mutual_inclusion', {
        parent      => 'foo',
        using-key   => 'nlx.lib.maybe_one',
        child       => 'bar',
        using-attrs => {}
    } ]

    [ 'subset-constraint', 'sc_artist_has_cds', {
        parent      => 'artists',
        using-key   => 'nlx.lib.Artists.pk_artist_id',
        child       => 'cds',
        using-attrs => { artist_id => 'artist_id' }
    } ]

Distributed Subset Constraint Specification

TODO.

Stimulus-Response Rule Specification

A stim_resp_rule node specifies a new stimulus-response rule that lives in a depot or subdepot. A stim_resp_rule node has 3 ordered elements: The first element is the Perl Str value stimulus-response-rule. The second element is a Name_payload, which is the stimulus-response rule's declared name. The third element is a stim_resp_rule_payload.

A stim_resp_rule_payload is a Perl Pair whose key and value are designated, in order, stimulus and response; stimulus is the Perl Str value after-mount (the kind of stimulus), and response is a PNSQNameChain_payload (the name of the recipe or procedure being invoked in response).

Examples:

    [ 'stimulus-response-rule', 'bootstrap', :after-mount<nlx.lib.main> ]

GENERIC VALUE EXPRESSIONS

An expr_name node has 2 ordered elements: The first element is the Perl Str value d ("data"). The second element is a Name_payload.

An expr_name node may alternately be formatted as a Perl Pair whose key and value are what would otherwise be the first and second node elements, respectively.

A named_expr node has 3 ordered elements: The first element is either of the 2 Perl Str values [::=, let]. The second element is a Name_payload and the third element is an expr node; the second element declares an explicit expression node name for the third element.

Examples:

    # an expr_name node #
    :d<foo_expr>

    # a named_expr node #
    [ '::=', 'bar_expr', [ 'func-invo', 'factorial', [:d<foo_expr>] ] ]

Generic Expression Attribute Accessors

An accessor node has 2-3 ordered elements, such that 2 elements makes it an acc_via_named and 3 elements makes it an acc_via_anon: The first element is the Perl Str value acc. The last element of an acc_via_named is a NameChain_payload, which is by itself the target of the accessor (naming both the other node plus its attribute to alias). The second element of an acc_via_anon is an expr node which is the other node whose attribute is being aliased. The last element of an acc_via_anon is a nonempty NameChain_payload and names the attribute.

Examples:

    # an accessor node of a named tuple-valued node #
    :acc<foo_t.bar_attr>

    # an accessor node of an anonymous tuple-valued node #
    ['acc',['func-invo','nlx.lib.tuple_res_func',[:d<arg>]],'quux_attr']

Generic Function Invocation Expressions

A func_invo node has 2-4 ordered elements: The first element is the Perl Str value func-invo. The second element is a PNSQNameChain_payload, which names the function to invoke. The last 1-2 elements provide arguments to the function invocation; either or both or none of an Array_payload element and a Tuple_payload element may be given. The Array_payload 3rd/4th element is for any anonymous (and ordered if multiple exist) arguments, and the Tuple_payload 3rd/4th element is for any named arguments; each Array_payload element or Tuple_payload element value is an expr node which is the argument value.

Examples:

    # zero params #
    :func-invo<Nothing>

    # single mandatory param #
    [ 'func-invo', 'median', [ :Bag( Bag.new(22,20,21,20,21,21,23) ) ] ]

    # single mandatory param #
    [ 'func-invo', 'factorial', { topic => 5 } ]

    # two mandatory params #
    [ 'func-invo', 'frac_quotient', { dividend => 43.7, divisor => 16.9 } ]

    # one mandatory 'topic' param, two optional #
    [ 'func-invo', 'nlx.lib.barfunc', [ :d<mand_arg> ],
        { oa1 => :d<opt_arg1>, oa2 => :d<opt_arg2> } ]

    # a user-defined function #
    [ 'func-invo', 'nlx.lib.foodb.bazfunc',
        { a1 => 52, a2 => 'hello world' } ]

    # two params named 'topic' and 'other' #
    [ 'func-invo', 'is_same', [ :d<foo>, :d<bar> ] ]

    # invoke the lexically innermost routine with 2 args #
    [ 'func-invo', 'rtn', [ :d<x>, :d<y> ] ]

Generic If-Else Expressions

An if_else_expr node has 4 ordered elements: The first element is either of the 2 Perl Str values if-else-expr and ??!!. The second element is the if condition expression; the third and fourth elements are the then and else result expressions, respectively; every one of the last 3 elements is an expr node.

Examples:

    [ 'if-else-expr', [ 'i-op', '>', [:d<foo>, 5] ], :d<bar>, :d<baz> ]

    [ 'if-else-expr',
        ['func-invo','is_empty',[:d<ary>]],
        :d<empty_result>,
        [ 'post-op', '.[]', [:d<ary>, 0] ]
    ]

    [ 'i-op', '~', ['My answer is: ', [ '??!!', :d<maybe>, 'yes', 'no' ]] ]

Generic Given-When-Default Expressions

A given_when_def_expr node has 3-4 ordered elements: The first element is the Perl Str value given-when-def-expr. The second element is an expr node which is the given common comparand. The optional third element is when_then, a Perl Seq|Array with 0..N elements, each of those being a 2-element Perl Seq|Array or a Perl Pair, where each element is an expr node; the first element / key is a when comparand, and the second element / value is the associated then result expression. The 4th/last element of a given_when_def_expr node is default result expression, which is an expr node.

Examples:

    [ 'given-when-def-expr',
        :d<digit>,
        [
            'T' => 10,
            'E' => 11,
        ],
        :d<digit>,
    ]

Material Reference Selector Expressions

A material_ref node has 2 ordered elements: The first element is the Perl Str value material-ref. The second element is a PNSQNameChain_payload, which names the routine or type to reference.

A curried_func node has 2-4 ordered elements: The first element is the Perl Str value curried-func. The second element is a PNSQNameChain_payload, which names the function to reference. The last 1-2 elements provide arguments for the function as per the last 1-2 elements of a func_invo node.

A material_ref node, or a curried_func node with zero curried arguments, may alternately be formatted as a Perl Pair whose key and value are what would otherwise be the first and second node elements, respectively.

Examples:

    # a higher-order function curried with 1 argument #
    [ 'curried-func', 'nlx.lib.filter',
        { search_term => :d<search_term> } ]

    # a reference to an updater #
    :material-ref<nlx.lib.swap>

    # a reference to a data type #
    :material-ref<nlx.lib.foo_type>

GENERIC PROCEDURE STATEMENTS

A stmt_name node has 2 ordered elements: The first element is the Perl Str value s. The second element is a Name_payload.

A stmt_name node may alternately be formatted as a Perl Pair whose key and value are what would otherwise be the first and second node elements, respectively.

A named_stmt node has 3 ordered elements: The first element is either of the 2 Perl Str values [::=, let]. The second element is a Name_payload and the third element is a proc_stmt node; the second element declares an explicit statement node name for the third element.

Examples:

    # a stmt_name node #
    :s<foo_stmt>

    # a named_stmt node #
    [ '::=', 'bar_stmt', [ 'proc-invo', 'nlx.lib.swap',
        {first => ['&',:d<first>], second => ['&',:d<second>]} ] ]

Generic Compound Statements

A compound_stmt node has 2 ordered elements: The first element is the Perl Str value compound-stmt. The second element is a Perl Seq|Array having zero or more elements where each element must be either a with_clause or a proc_var or a named_expr or a proc_stmt; it is interpreted as per a nonempty procedure body, which has exactly the same format.

Examples:

    :compound-stmt[
        [ 'var', 'message', 'Text' ],
        [ 'proc-invo', 'read_Text_line', [ ['&',:d<message>] ] ],
        [ 'proc-invo', 'write_Text_line', [ :d<message> ] ],
    ]

Multi-Update Statements

A multi_upd_stmt node has 2 ordered elements: The first element is the Perl Str value multi-upd-stmt. The second element is a Perl Seq|Array; it is interpreted as per a nonempty recipe body, which has exactly the same format.

Examples:

    :multi-upd-stmt[
        [ '::=', 'order_id', [ '??!!',
            [ 'func-invo', 'is_empty', [:d<orders>] ],
            1,
            [ 'post-op', '++', [[ 'func-invo', 'max', [
                [ 'func-invo', 'Set_from_attr',
                    [:d<orders>], {name => :Name<order_id>} ]
            ] ]] ]
        ] ],

        [ 'proc-invo', 'assign_insertion', [ ['&',[:d<orders>]],
            [ '%', { order_id => :d<order_id>, date => '2011-03-04' } ]
        ] ],

        [ 'proc-invo', 'assign_union', [ ['&',[:d<order_details>]],
            '@' => <order_id prod_code qty> => Set.new(
                [ :d<order_id>, 'COG' , 20, ],
                [ :d<order_id>, 'CAM' , 10, ],
                [ :d<order_id>, 'BOLT', 70, ],
            )
        ] ],
    ]

Generic Procedure Invocation Statements

A proc_invo node has 2-4 ordered elements: The first element is the Perl Str value proc-invo. The second element is a PNSQNameChain_payload, which names the procedure to invoke. The last 1-2 elements provide arguments to the procedure invocation; either or both or none of an Array_payload element and a Tuple_payload element may be given. The Array_payload 3rd/4th element is for any anonymous (and ordered if multiple exist) arguments, and the Tuple_payload 3rd/4th element is for any named arguments; each Array_payload element or Tuple_payload element value is the possibly tagged argument value (PTAV). For each PTAV, if the argument is for a read-only parameter, then the PTAV is just an expr node which is the argument value; if the argument is for a subject-to-update parameter, then the PTAV is a Perl Seq|Array with exactly 2 elements, where the first element is the Perl Str value &, and the second element is the same expr node that the PTAV would have been were this for a read-only parameter.

Examples:

    # two mandatory params, one s-t-u, one r-o #
    [ 'proc-invo', 'assign', [ ['&',:d<foo>], 3 ] ]

    # same as previous #
    [ 'proc-invo', 'assign', [ 3, ['&',:d<foo>] ] ]

    # still same as previous but with all-named syntax #
    [ 'proc-invo', 'assign', { target => ['&',:d<foo>], v => 3 } ]

    # three mandatory params #
    [ 'proc-invo', 'nlx.lib.lookup', { addr => ['&',:d<addr>],
        people => :d<people>, name => :d<name> } ]

    [ 'proc-invo', 'fetch_trans_instant', [ ['&',:d<now>] ] ]

    [ 'proc-invo', 'prompt_Text_line',
        [ ['&',:d<name>], 'Enter a person\'s name: ' ] ]

    [ 'proc-invo', 'Integer.fetch_random',
        [ ['&',:d<rand>], :d<interval> ] ]

Generic Try-Catch Statements

A try_catch_stmt node has 2-3 ordered elements: The first element is the Perl Str value try-catch. The second element is a proc_stmt node having the try routine to unconditionally invoke first. The optional third element is a proc_stmt node having the catch routine to execute iff try throws an exception.

Examples:

    [ 'try-catch',
        :proc-invo<nlx.lib.attempt_the_work>,
        :proc-invo<nlx.lib.deal_with_failure>
    ]

Generic If-Else Statements

An if_else_stmt node has 3-4 ordered elements: The first element is the Perl Str value if-else-stmt. The second element is the if condition expression (an expr node). The third element is the then statement (a proc_stmt node). The optional fourth/last element is the else statement (a proc_stmt node).

Examples:

    [ 'if-else-stmt',
        :d<out_of_options>,
        :proc-invo<nlx.lib.give_up>,
        :proc-invo<nlx.lib.keep_going>
    ]

Generic Given-When-Default Statements

A given_when_def_stmt node has 3-4 ordered elements: The first element is the Perl Str value given-when-def-stmt. The second element is an expr node which is the given common comparand. The optional third element is proc_when_then, a Perl Seq|Array with 0..N elements, each of those being a 2-element Perl Seq|Array or a Perl Pair; the first element / key is a when comparand (an expr node), and the second element / value is the associated then result statement (a proc_stmt node). The optional 4th/last element of a given_when_def_stmt node is default_stmt statement, which is a proc_stmt node.

Examples:

    [ 'given-when-def-stmt',
        :d<picked_menu_item>,
        [
            'v' => :proc-invo<nlx.lib.screen_view_record>,
            'a' => :proc-invo<nlx.lib.screen_add_record>,
            'd' => :proc-invo<nlx.lib.screen_delete_record>
        ],
        :proc-invo<nlx.lib.display_bad_choice_error>,
    ]

Procedure Leave, Iterate, and Loop Statements

A leave_stmt node has 1-2 ordered elements: The first element is the Perl Str value leave. The optional second element is a Name_payload which names the parent statement node to abort; it defaults to the empty string if not specified.

An iterate_stmt node has 1-2 ordered elements: The first element is the Perl Str value iterate. The optional second element is a Name_payload which names the parent statement node to redo; it defaults to the empty string if not specified.

A loop_stmt node has 2 ordered elements: The first element is the Perl Str value loop. The second element is a proc_stmt node having the statement to repeatedly execute.

Examples:

    [ '::=', 'lookup_person', loop => :compound-stmt[
        [ 'proc-invo', 'prompt_Text_line',
            [ ['&',:d<name>], 'Enter a name to search for: ' ] ],
        [ 'given-when-def-stmt', :d<name>,
            [ '' => :leave<lookup_person> ] ],
        [ 'proc-invo', 'nlx.lib.do_search', {
            name => :d<name>,
            not_found => ['&',:d<not_found>],
            report_text => ['&',:d<report_text>]
        } ],
        [ 'if-else-stmt', :d<not_found>, :compound-stmt[
            [ 'proc-invo', 'write_Text_line', ['No person matched'] ],
            :iterate<lookup_person>
        ] ],
        [ 'proc-invo', 'write_Text_line', [ :d<report_text> ] ],
    ] ]

DEPRECATED - FUNCTION INVOCATION ALTERNATE SYNTAX EXPRESSIONS

A func_invo_alt_syntax node has 3-4 ordered elements: The first element is one of the 3 Perl Str values [i-op, pre-op, post-op], depending on whether it represents infix, prefix, or postfix syntax, respectively. The second element is a Perl Str value, hereafter referred to as op or keyword, which determines the function to invoke. The third element is (usually) a Perl Seq|Array, hereafter referred to as main op args, which is an ordered list of 1-N mandatory inputs to the function invocation. The (optional) fourth element is a Perl Mapping|Hash, hereafter referred to as extra op args, which is a named list of optional function inputs. The number and format of elements of either main op args or extra op args varies depending on op. Note that, when a main op args would just contain a single element, such as when it is for a monadic operator, it may alternately be formatted as what is otherwise just its sole (node) element iff that node is not formatted as a Perl Seq|Array.

Simple Commutative N-adic Infix Reduction Operators

A comm_infix_reduce_op_invo node has 2-N main op args, each of which is an expr node. Note that the main op args may alternately be given as a Perl Bag|KeyBag|Set|KeySet rather than a Perl Seq|Array.

Examples:

    [ 'i-op', 'min', [ :d<a>, :d<b>, :d<c> ] ]

    [ 'i-op', 'max', [ :d<a>, :d<b>, :d<c> ] ]

    [ 'i-op', 'and', [ Bool::True, Bool::False, Bool::True ] ]

    [ 'i-op', 'or', [ Bool::True, Bool::False, Bool::True ] ]

    [ 'i-op', 'xor', [ Bool::True, Bool::False, Bool::True ] ]

    [ 'i-op', '+', [ 14, 3, -5 ] ]

    [ 'i-op', '*', [ -6, 2, 25 ] ]

    [ 'i-op', '+', [ 4.25, -0.002, 1.0 ] ]

    [ 'i-op', '*', [ 69.3, 15 * 2 ** 6, 49/23 ] ]

    [ 'i-op', '∪', [ :Set( Set.new( 1, 3, 5 ) ),
        :Set( Set.new( 4, 5, 6 ) ), :Set( Set.new( 0, 9 ) ) ] ]

    [ 'i-op', '∩', [ :Set( Set.new( 1, 3, 5, 7, 9 ) ),
        :Set( Set.new( 3, 4, 5, 6, 7, 8 ) ), :Set( Set.new( 2, 5, 9 ) ) ] ]

Simple Non-commutative N-adic Infix Reduction Operators

A noncomm_infix_reduce_op_invo node has 2-N main op args, each of which is an expr node.

Examples:

    [ 'i-op', '[<=>]', [ Order::Same, Order::Less, Order::More ] ]

    [ 'i-op', '~', [ :16{DEAD}, :2{10001101}, :16{BEEF} ] ]

    [ 'i-op', '~', [ 'hello', ' ', 'world' ] ]

    [ 'i-op', '~', [ :Array[24, 52], :Array[-9], :Array[0, 11, 24, 7] ] ]

    [ 'i-op', '//', [ :d<a>, :d<b>, 42 ] ]

Simple Symmetric Dyadic Infix Operators

A sym_dyadic_infix_op_invo node has exactly 2 main op args, each of which is an expr node; which function arguments get which main op args isn't significant.

Examples:

    [ 'i-op', '=', [ :d<foo>, :d<bar> ] ]

    [ 'i-op', '≠', [ :d<foo>, :d<bar> ] ]

    [ 'i-op', 'nand', [ Bool::False, Bool::True ] ]

    [ 'i-op', '|-|', [ 15, 17 ] ]

    [ 'i-op', '|-|', [ 7.5, 9.0 ] ]

Simple Non-symmetric Dyadic Infix Operators

A nonsym_dyadic_infix_op_invo node has exactly 2 main op args, each of which is an expr node; the first and second main op args are lhs and rhs, respectively.

Examples:

    [ 'i-op', 'isa', [ :d<bar>, :material-ref<nlx.lib.foo_type> ] ]

    [ 'i-op', '!isa', [ :d<bar>, :material-ref<nlx.lib.foo_type> ] ]

    [ 'i-op', 'as', [ :d<scalar>, :material-ref<Int> ] ]

    [ 'i-op', 'asserting', [:d<int>, [ 'i-op', '≠', [:d<int>, 0] ]] ]

    [ 'i-op', 'implies', [ Bool::True, Bool::False ] ]

    [ 'i-op', '<', [ :d<foo>, :d<bar> ] ]

    [ 'i-op', '>', [ :d<foo>, :d<bar> ] ]

    [ 'i-op', '≤', [ :d<foo>, :d<bar> ] ]

    [ 'i-op', '≥', [ :d<foo>, :d<bar> ] ]

    [ 'i-op', '-', [ 34, 21 ] ]

    [ 'i-op', 'exp', [ 2, 63 ] ]

    [ 'i-op', '-', [ 9.2, 0.1 ] ]

    [ 'i-op', '/', [ 0b101.01, 0b11.0 ] ]

    [ 'i-op', '~#', [ '-', 80 ] ]

    [ 'i-op', '∈', [ :d<a>, 1..5 ] ]

    [ 'i-op', '¬in;', [ :d<foo>, :d<min>..^:d<max> ] ]

    [ 'i-op', '∖', [:Set(Set.new( 8, 4, 6, 7 )), :Set(Set.new( 9, 0, 7 ))] ]

    [ 'i-op', '÷', [ '@' => <x y> => Set.new( [ 5, 6 ], [ 3, 6 ] ),
        '@' => Set.new( { y => 6 } ) ] ]

Simple Monadic Prefix Operators

A monadic_prefix_op_invo node has exactly 1 main op arg, which is an expr node.

Examples:

    [ 'pre-op', 'not, Bool::True ]

    [ 'pre-op', 'abs, -23 ]

    [ 'pre-op', 'abs, -4.59 ]

    [ 'pre-op', '#, :Set(Set.new( 5, -1, 2 )) ]

    [ 'pre-op', '%, :d<relvar> ]

    [ 'pre-op', '@, :d<tupvar> ]

Simple Monadic Postfix Operators

A monadic_postfix_op_invo node has exactly 1 main op arg, which is an expr node.

Examples:

    [ 'post-op', '++', 13 ]

    [ 'post-op', '--', 4 ]

    [ 'post-op', '!', 5 ]

Simple Postcircumfix Operators

A postcircumfix_op_invo node has exactly 2-3 main op args, where the first is an expr node that defines the primary input value for the operator and the other 1-2 provide attribute names that customize the operation.

Note that for the [] op, the min_index, interval_boundary_kind, max_index are collectively the 2nd main op arg which is an SPInterval node payload that defines an sp_interval_of.NNInt.

Examples:

    [ 'post-op', '.{:}', [:d<birthday>, 'date', 'day'] ]

    [ 'post-op', '.{}', [:d<pt>, 'city'] ]

    [ 'post-op', '{<-}', [:d<pt>, {pnum=>'pno', locale=>'city'}] ]

    [ 'post-op', '{<-}', [:d<pr>, {pnum=>'pno', locale=>'city'}] ]

    [ 'post-op', '{:}', [:d<birthday>, 'date', ['year','month']] ]

    [ 'post-op', '{}', [:d<pt>, ['color','city']] ]

    [ 'post-op', '{}', [:d<pr>, ['color','city']] ]

    [ 'post-op', '{}', [:d<pt>, []] ]  # null projection #

    [ 'post-op', '{}', [:d<pr>, []] ]  # null projection #

    [ 'post-op', '{:!}', [:d<rnd_rule>, ['round_meth']] ]  # radix,min_exp #

    [ 'post-op', '{!}', [:d<pt>, ['pno','pname','weight']] ]

    [ 'post-op', '{!}', [:d<pr>, ['pno','pname','weight']] ]

    [ 'post-op', '{%<-}', [:d<person>, 'name', ['fname','lname']] ]

    [ 'post-op', '{%<-}', [:d<people>, 'name', ['fname','lname']] ]

    [ 'post-op', '{%<-!}', [:d<person>,'all_but_name',['fname','lname']] ]

    [ 'post-op', '{%<-!}', [:d<people>,'all_but_name',['fname','lname']] ]

    [ 'post-op', '{<-%}', [:d<person>, ['fname','lname'], 'name'] ]

    [ 'post-op', '{<-%}', [:d<people>, ['fname','lname'], 'name'] ]

    [ 'post-op', '{@<-}', [:d<orders>, 'vendors', ['vendor']] ]

    [ 'post-op', '{@<-!}', [:d<orders>, 'all_but_vendors', ['vendor']] ]

    [ 'post-op', '{<-@}', [:d<orders>, ['vendor'], 'vendors'] ]

    [ 'post-op', '{#@<-!}',
        [:d<people>, 'count_per_age_ctry', ['age','ctry']] ]

    [ 'post-op', '.{*}', :d<maybe_foo> ]

    [ 'post-op', '.[]', [:d<ary>, 3] ]

    [ 'post-op', '[]', [:d<ary>, 10..14] ]

Numeric Operators That Do Rounding

A num_op_invo_with_round node has exactly 2-3 main op args, each of which is an expr node that defines an input value for the operator. When there are 2 main op args, the first and second args are expr and round_rule, respectively. When there are 3 main op args, the first, second and third args are lhs, rhs and round_rule, respectively.

Examples:

    [ 'i-op', 'div', [ 5, 3, :RoundMeth<ToZero> ] ]

    [ 'i-op', 'mod', [ 5, 3, :RoundMeth<ToZero> ] ]

    [ 'i-op', 'round', [:d<foo>, :RatRoundRule[10,-2,'HalfEven']] ]

    [ 'i-op', '**', [ 2.0, 0.5, :RatRoundRule[2,-7,'ToZero'] ] ]

    [ 'i-op', 'log', [ 309.1, 5.4, :RatRoundRule[10,-4,'HalfUp'] ] ]

    [ 'pre-op', 'e**, [ 6.3, :RatRoundRule[10,-6,'Up'] ] ]

    [ 'post-op', 'log-e', [ 17.0, :RatRoundRule[3,-5,'Down'] ] ]

Order Comparison Operators

An ord_compare_op_invo node has exactly 2 main op args, each of which is an expr node. The first and second args are lhs and rhs, respectively. Details on the extra op args are pending.

Examples:

    [ 'i-op', '<=>', [ :d<foo>, :d<bar> ] ]

DEPRECATED - PROCEDURE INVOCATION ALTERNATE SYNTAX STATEMENTS

A proc_invo_alt_syntax node has 3-4 ordered elements: The first element is one of the 3 Perl Str values [i-op, pre-op, post-op], depending on whether it represents infix, prefix, or postfix syntax, respectively. The second element is a Perl Str value, hereafter referred to as op or keyword, which determines the procedure to invoke. The third element is (usually) a Perl Seq|Array, hereafter referred to as main op args, which is an ordered list of 1-N mandatory inputs to the procedure invocation. The (optional) fourth element is a Perl Mapping|Hash, hereafter referred to as extra op args, which is a named list of optional procedure inputs. The number and format of elements of either main op args or extra op args varies depending on op. Note that, when a main op args would just contain a single element, such as when it is for a monadic operator, it may alternately be formatted as what is otherwise just its sole (node) element iff that node is not formatted as a Perl Seq|Array.

Procedure Simple Monadic Postfix Operators

An proc_monadic_postfix_op_invo node has exactly 1 main op arg, which is an expr node.

Examples:

    [ 'post-op', ':=++', :d<counter> ]

    [ 'post-op', ':=--', :d<countdown> ]

Procedure Simple Non-symmetric Dyadic Infix Operators

A proc_nonsym_dyadic_infix_op_invo node has exactly 2 main op args, each of which is an expr node; the first and second main op args are lhs and rhs, respectively.

Examples:

    # assign 3 to foo #
    [ 'i-op', ':=', [ :d<foo>, 3 ] ]

    # swap x and y using pseudo-variables #
    [ 'i-op', ':=', [ ['%',{0=>:d<x>,1=>:d<y>}], ['%',{0=>:d<y>,1=>:d<x>}] ] ]

    # delete every person in people whose age is either 10 or 20 #
    [ 'i-op', ':=!matching', [ :d<people>,
        '@' => Set.new( { age => 10 }, { age => 20 } ) ] ]

SEE ALSO

Go to Muldis::D for the majority of distribution-internal references, and Muldis::D::SeeAlso for the majority of distribution-external references.

AUTHOR

Darren Duncan (darren@DarrenDuncan.net)

LICENSE AND COPYRIGHT

This file is part of the formal specification of the Muldis D language.

Muldis D is Copyright © 2002-2011, Muldis Data Systems, Inc.

See the LICENSE AND COPYRIGHT of Muldis::D for details.

TRADEMARK POLICY

The TRADEMARK POLICY in Muldis::D applies to this file too.

ACKNOWLEDGEMENTS

The ACKNOWLEDGEMENTS in Muldis::D apply to this file too.

cpanm Muldis::D

perl -MCPAN -e shell
install Muldis::D