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We can use a literal numeral or an Int with a sub that takes a native:
<Zoffix> m: sub foo (int) { say "OK!" }; foo 2
<camelia> rakudo-moar d03459: OUTPUT«OK!»
<Zoffix> m: sub foo (int) { say "OK!" }; my Int $x = 2; foo $x
<camelia> rakudo-moar d03459: OUTPUT«OK!»
But, such auto-unboxing doesn't work if we use a multi instead:
<Zoffix> m: multi foo (int) { say "OK!" }; foo 2
<camelia> rakudo-moar d03459: OUTPUT«Cannot resolve caller foo(Int);
none of these signatures match: (int) in block <unit> at <tmp>
line 1»
<Zoffix> m: multi foo (int) { say "OK!" }; my Int $x = 2; foo $x
<camelia> rakudo-moar d03459: OUTPUT«Cannot resolve caller foo(Int);
none of these signatures match: (int) in block <unit> at <tmp>
line 1»
Even though auto-boxing for natives works regardless of whether we
have a multi:
<Zoffix> m: sub foo (Int) { say "OK!" }; my int $x = 2; foo $x
<camelia> rakudo-moar d03459: OUTPUT«OK!»
<Zoffix> m: multi foo (Int) { say "OK!" }; my int $x = 2; foo $x
<camelia> rakudo-moar d03459: OUTPUT«OK!»
I found this bug while out on a hunt for another one, and it looks
like the solutions might be very similar, so I'm filing this with a
tentative "leave it with me."
As part of this issue and the one I'm resolving, I had to write out a
list of rules of how literals, natives, and their related types behave
in multi resolution:
(I describe int/Int, but same applies for other natives that have
a boxed Perl 6 equivalent):
0) Literal: treat as Int
1) Int:
1.1) Use as Int, if have candidate
1.2) Use as native, if:
1.2.1) have native candidate
1.2.2) size fits
2) Native:
2.1) Use as native, if have candidate
2.2) Use as Int, if have candidate
And so we have:
my int $i = 2; # used in all examples to indicate native int
multi foo (int $x) {say "native" };
foo 2; # native; 0 => 1 => 1.2
multi foo (Int $x) {say "other Int" };
foo 2; # other Int; 0 => 1 => 1.1
multi foo (int $x) {say "native" };
foo $i; # native; 2 => 2.1
multi foo (Int $x) {say "other Int" };
foo $i; # other Int; 2 => 2.2
multi foo (int $x) {say "native" };
multi foo (Int $x) {say "other Int" };
foo 2; # other Int; 0 => 1 => 1.1
foo $i; # native; 2 => 2.1
multi foo (int $x) {say "native" };
multi foo (Str $x) {say "other Str" };
foo 2; # native; 0 => 1 => 1.2
foo $i; # native; 2 => 2.1
multi foo (Int $x) {say "other Int" };
multi foo (Str $x) {say "other Str" };
foo 2; # other Int; 0 => 1 => 1.1
foo $i; # other Int; 2 => 2.2
multi foo (int $x) {say "native" };
multi foo (Int $x) {say "other Int" };
foo 2; # other Int; 0 => 1 => 1.1
foo 2**100; # other Int; 0 => 1 => 1.1
multi foo (int $x) {say "native" };
foo 2; # native; 0 => 1.2
foo 2**100; # X::Multi::NoMatch (no Int candidate);
# 0 => 1 => 1.2 => 1.2.2 (fails to match at this point)
multi foo (int $x, int $y) {say "native" };
multi foo (Int $x, Int $y) {say "other Int" };
foo 2, $i; # other Int; (0 => 1 => 1.1), (2 => 2.1)
foo 2, 2; # other Int; (0 => 1 => 1.1), (0 => 1 => 1.1)
foo $i, $i; # native; (2 => 2.1), (2 => 2.1)
multi foo (int $x, int $y) {say "native" };
multi foo (Int $x, int $y) {say "Int + native" };
multi foo (Int $x, Int $y) {say "other Int" };
foo 2, $i; # Int + native; (0 => 1 => 1.1), (2 => 2.1)
foo 2, 2; # other Int; (0 => 1 => 1.1), (0 => 1 => 1.1)
foo $i, $i; # native; (2 => 2.1), (2 => 2.1)
