Typed subroutines

gistfile1.pl

use Test;
plan 9;

subset TwoArgSub of Sub where {
    .signature.params == 2
};

my TwoArgSub $a;

lives_ok { $a = sub ($a, $b)     { } };
dies_ok  { $a = sub ()           { } };
dies_ok  { $a = sub ($a)         { } };
dies_ok  { $a = sub ($a, $b, $c) { } };

subset TakesIntAndString of Sub where {
    .signature.params == 2
    and .signature.params[0].type ~~ Int
    and .signature.params[1].type ~~ Str
}

my TakesIntAndString $b;

lives_ok { $b = sub (Int $a, Str $b)     { } };
dies_ok  { $b = sub (Int $a, $b)         { } };
dies_ok  { $b = sub ($a, Str $b)         { } };
dies_ok  { $b = sub (Str $a, Int $b)     { } };
dies_ok  { $b = sub (Int $a, Str $b, $c) { } };