NAME

Sub::Operable - apply Perl built-in operators to coderefs

SYNOPSIS

  use Sub::Operable 'subop';
  
  # f(x) = x²
  #
  my $f = subop { $_ ** 2 };
  
  # f(4) = 4²
  #      = 16
  #
  say $f->(4);   # ==> 16
  
  # g(x) = 2x
  #
  my $g = subop { 2 * $_ };
  
  # h = f + g + 3
  #
  my $h = $f + $g + 3;
  
  # h(10) = f(10) + g(10) + 3
  #       = 10²   + 2(10) + 3
  #       = 100   + 20    + 3
  #       = 123
  #
  say $h->(10);   # ==> 123

DESCRIPTION

Sub::Operator allows you to define functions and apply operations to the functions like you can in algebra class.

All the standard built-in binary, string, numeric, and comparison operators should work fine. Operators like += which mutate their operands are not supported.

Additionally if you call a Sub::Operator-enabled function passing another Sub::Operator-enabled function as an argument, you get a composed Sub::Operator-enabled function as the result.

  # Assume $f and $g defined as above.
  
  # m(x) = g( f(x) )
  #
  my $m = $g->( $f );
  
  # m(10) = g( f(10) )
  #       = g( 10² )
  #       = g( 100 )
  #       = 2 * 100
  #       = 200
  #
  say $m->(10);   # ==> 200

Object-Oriented Constructor

  use Sub::Operable;
  
  my $coderef = 'Sub::Operable'->new(sub { ... });

When the coderefs are called, $_ will be an alias of $_[0].

Shortcut Constructor

  use Sub::Operable qw( subop );
  
  my $coderef = subop { ... };

When the coderefs are called, $_ will be an alias of $_[0].

Utility Function

  use Sub::Operable qw( isa_Sub_Operable );
  
  my $bool = isa_Sub_Operable( $coderef );

Constants

You can get lists of supported operators:

  use Sub::Operable;
  
  my @prefix = Sub::Operable::PREFIX_OPS;
  my @infix  = Sub::Operable::INFIX_OPS;

Symbol Table Frickery

You don't have to just deal with coderefs. You can put these functions into the symbol table.

  use Sub::Operable 'subop';
  
  # f(x) = x²
  #
  *f = subop { $_ ** 2 };
  
  # f(4) = 4²
  #      = 16
  #
  say f(4);   # ==> 16
  
  # g(x) = 2x
  #
  *g = subop { 2 * $_ };
  
  # h = f + g + 3
  #
  *h = \&f + \&g + 3;
  
  # h(10) = f(10) + g(10) + 3
  #       = 10²   + 2(10) + 3
  #       = 100   + 20    + 3
  #       = 123
  #
  say h(10);   # ==> 123

BUGS

Please report any bugs to http://rt.cpan.org/Dist/Display.html?Queue=Sub-Operable.

SEE ALSO

curry, I guess?

AUTHOR

Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE

This software is copyright (c) 2020 by Toby Inkster.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTIES

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

cpanm Sub::Operable

perl -MCPAN -e shell
install Sub::Operable