Add types to signature and make multi

Fix several cases where Type.method would give a "cannot access attribute in
a type object": should that happen now, it should give you a "cannot find
candidate", or should just work.

src/core/List.pm

@@ -45,11 +45,11 @@ my class List does Positional { # declared in BOOTSTRAP
         nqp::p6list($args, self.WHAT, Mu);
     }
 
-    method Bool()       { self.gimme(1).Bool }
-    method Int()        { self.elems }
-    method end()        { self.elems - 1 }
-    multi method Numeric(List:D:)  { self.elems }
-    multi method Str(List:D:)      { self.join(' ') }
+    multi method Bool(List:D:)    { self.gimme(1).Bool }
+    multi method Int(List:D:)     { self.elems }
+    multi method end(List:D:)     { self.elems - 1 }
+    multi method Numeric(List:D:) { self.elems }
+    multi method Str(List:D:)     { self.join(' ') }
 
     # Pretend we're a Match assuming we're a list of Matches
     method to()         { self.elems ?? self[self.end].to !! Nil }

src/core/OS.pm

@@ -16,17 +16,9 @@ my class Proc::Status {
         $!exit   = $new_status +> 8;
         $!signal = $new_status +& 0xFF;
     }
-    multi method status() {
-        ($!exit +< 8) +| $!signal
-    }
-
-    method Numeric {
-        $!exit
-    }
-
-    method Bool {
-        $!exit == 0
-    }
+    multi method status(Proc::Status:D:)  { ($!exit +< 8) +| $!signal }
+    multi method Numeric(Proc::Status:D:) { $!exit }
+    multi method Bool(Proc::Status:D:)    { $!exit == 0 }
 }
 
 # vim: ft=perl6 expandtab sw=4

src/core/Setty.pm

@@ -13,9 +13,9 @@ my role Setty does QuantHash {
     method exists_key($k --> Bool) {
         so ( %!elems && nqp::existskey(%!elems, nqp::unbox_s($k.WHICH)) );
     }
-    method Bool { %!elems.Bool }
+    multi method Bool(Setty:D:) { %!elems.Bool }
 
-    method hash(--> Hash) {
+    multi method hash(Setty:D: --> Hash) {
         my %e;
         %e{$_} = True for %!elems.values;
         %e;

src/core/StrDistance.pm

@@ -3,15 +3,10 @@ my class StrDistance is Cool {
     has Str $.after;
     has Int $!distance;
 
-    method Bool() {
-        $.before ne $.after
-    }
-
-    method Numeric() {
-        self.Int
-    }
+    multi method Bool(StrDistance:D:)    { $.before ne $.after }
+    multi method Numeric(StrDistance:D:) { self.Int }
 
-    method Int() {
+    multi method Int(StrDistance:D:) {
         $!distance //= do {
             my @s = *, $.before.comb;
             my @t = *, $.after.comb;