The Keyword

This requires very little explanation. If you're no fun, and don't like the name "fun", you can export it with a different name:

   use Kavorka fun => { -as => 'function' };

The Function Name

If present, it specifies the name of the function being defined. If no name is present, the declaration is an expression that evaluates to a reference to the function in question.

Functions are automatically forward-declared; a la

   sub foobar ($$);

but are installed into the symbol table at run-time. So this works:

   if ($ENV{DEBUG}) {
      fun foobar { ... }
   }
   else {
      fun foobar { ... }
   }

It is possible to install the function at compile time using the "begin" trait:

   fun foobar but begin { ... }

It is possible to define lexical functions using a lexical variable for a function name:

   fun my $add ($x, $y) {
      $x + $y;
   }
   
   my $sum = $add->(20, 22);

The Signature

See Kavorka::Manual::Signatures.

Traits

See Kavorka::Manual::ExtendingKavorka.

The Prototype

See Kavorka::Manual::PrototypeAndAttributes.

The Attributes

Attributes may alternatively be provided before the signature.

See Kavorka::Manual::PrototypeAndAttributes.

The Function Body

This is more or less what you'd expect from the function body you'd write with sub, however the lexical variables for parameters are pre-declared and pre-populated.

"f", "func", and "function"

These are all aliases for "fun", though not exported by default.

   use v5.14;
   use Kavorka qw( function f );
   
   function make_plusser (Num $x = 1)
   {
      return f(Num $y) { $x + $y };
   }
   
   my $plusser = make_plusser();
   say $plusser->(41);   # says 42