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Re^2: Near-free function currying in Perl

by dragonchild (Archbishop)
on Nov 17, 2004 at 16:56 UTC ( #408472=note: print w/replies, xml ) Need Help??


in reply to Re: Near-free function currying in Perl
in thread Near-free function currying in Perl

package AutoCurry; require v5.6.1; use Attribute::Handlers::Prospective; sub UNIVERSAL::curry : ATTR(CODE,RAWDATA) { my ($package, $symbol, $referent, $attr, $data, $phase) = @_; my $num = () = $data =~ /(\$)/g; *{"$package".'::'.*{$symbol}{NAME}} = sub { if (@_ < $num) { my @x = @_; return sub { $referent->(@x, @_ ) }; } $referent->(@_); }; } 1; __END__ ############# demo.pl ############# #!perl use strict; use warnings; use AutoCurry; sub foo : curry($$$) { print "Hello @_\n"; }; foo( 'a', 'b', 'c' ); my $ref = foo('d','e'); $ref->('f'); $ref->('g');

Obviously, improvements can be made, but I think this does what is desired. There is a slight performance penalty, but it's not bad at all.

Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

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Re^3: Near-free function currying in Perl
by stvn (Monsignor) on Nov 17, 2004 at 17:11 UTC

    LOL, you beat me by only a few minutes, I was just going to posts this.

    Although to be honest, neither of our implementations, nor Tom's do what Haskell and Standard ML do, which is too keep currying until all the functions arguments are satisfied.

    my $curried_foo = foo(1); my $even_more_curried_foo = $curried_foo->(2); print $even_more_curried_foo->(3); # now we execute the function
    And from my (limited) understanding of prototypes, it seems that this may not be possible since seems it is difficult to assign an attribute to a closure.

    -stvn
      Easily fixed.
      package Demo; require v5.6.1; use Attribute::Handlers::Prospective; sub UNIVERSAL::curry : ATTR(CODE,RAWDATA) { my ($package, $symbol, $referent, $attr, $data, $phase) = @_; my $num = () = $data =~ /(\$)/g; my $subname = "$package".'::'.*{$symbol}{NAME}; *$subname = sub { if (@_ < $num) { my @x = @_; return sub { $subname->(@x, @_ ) }; } $referent->(@_); }; } 1; __END__

      Being right, does not endow the right to be rude; politeness costs nothing.
      Being unknowing, is not the same as being stupid.
      Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
      Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

        Very nice ++

        -stvn

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