---
name: "Kavorka::Manual::Functions"
section: "3pm"
platform: "linux"
package: "libkavorka-perl"
version: "0.039-3"
release: "Debian 10 (Buster)"
platforms: ["linux"]
url: "https://new.carta.tech/Kavorka::Manual::Functions"
---

# Kavorka::Manual::Functions(3pm)

fun keyword

## NAME

Kavorka::Manual::Functions - fun keyword

## DESCRIPTION

Kavorka provides the `"fun"` keyword for the purpose of defining functions (as against methods, etc).

The anatomy of a function:

- 1\.

  The keyword introducing the function.

- 2\.

  The function name (optional).

- 3\.

  The signature (optional).

- 4\.

  Traits (optional).

- 5\.

  The prototype (optional).

- 6\.

  The attribute list (optional).

- 7\.

  The function body.

Example:

```
   #  (1) (2)    (3)          (4)     (5)   (6)     (7)
      fun foobar ($foo, $bar) is cool :($$) :cached { return $foo + $bar }

   #          (1) (6)
      my $f = fun { return $_[0] + $_[1] };
```

### 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
```

## BUGS

Please report any bugs to \<http://rt.cpan.org/Dist/Display.html?Queue=Kavorka\>.

## SEE ALSO

Kavorka::Manual, Kavorka::Manual::Signatures, Kavorka::Manual::PrototypeAndAttributes, Kavorka::Manual::MultiSubs.

## AUTHOR

Toby Inkster \<tobyink@cpan.org\>.

## COPYRIGHT AND LICENCE

This software is copyright (c) 2013-2014, 2017 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.