NAME

Sub::Curried - Currying of subroutines via a new 'curry' declarator

SYNOPSIS

 curry add_n_to ($n, $val) {
    return $n+$val;
 }

 my $add_10_to = add_n_to( 10 );

 say $add_n_to->(4);  # 14

 # but you can also
 say add_n_to(10,4);  # also 14

 # or more traditionally
 say add_n_to(10)->(4);

DESCRIPTION

Currying and Partial Application come from the heady world of functional programming, but are actually useful techniques. Partial Application is used to progressively specialise a subroutine, by pre-binding some of the arguments.

Partial application is the generic term, that also encompasses the concept of plugging in "holes" in arguments at arbitrary positions. Currying is (I think) more specifically the application of arguments progressively from left to right until you have enough of them.

SEE ALSO

Devel::Debug provides the magic (yes, there's a teeny bit of code generation involved, but it's not a global filter, rather a localised parsing hack).

There are several modules on CPAN that already do currying or partial evaluation:

• Perl6::Currying - Filter based module prototyping the Perl 6 system
• Sub::Curry - seems rather complex, with concepts like blackholes and antispices. Odd.
• AutoCurry - creates a currying variant of all existing subs automatically. Very odd.
• Sub::DeferredPartial - partial evaluation with named arguments (as hash keys). Has some great debugging hooks (the function is a blessed object which displays what the current bound keys are).
• Attribute::Curried - exactly what we want minus the sugar. (The attribute has to declare how many arguments it's expecting)

AUTHOR and LICENSE

 (c)2008 osfameron@cpan.org

This module is distributed under the same terms and conditions as Perl itself.

Please submit bugs to RT or shout at me on IRC (osfameron on #london.pm on irc.perl.org)