Port Set from niecza

src/core/Set.pm

@@ -0,0 +1,61 @@
+my class Set is Iterable does Associative {
+    has %!elems;
+
+    method keys { %!elems.keys }
+    method values { %!elems.values }
+    method elems returns Int { %!elems.elems }
+    method exists($a) returns Bool { %!elems.exists($a) }
+    method Bool { %!elems.Bool }
+    method Numeric { %!elems.Numeric }
+    method hash { %!elems.hash }
+    method at_key($k) { ?(%!elems{$k} // False) }
+    method exists_key($k) { self.exists($k) }
+
+    # Constructor
+    method new(*@args --> Set) {
+        my %e;
+        sub register-arg($arg) {
+            given $arg {
+                when Pair { %e{.key} = True; }
+                when Set | KeySet { for .keys -> $key { %e{$key} = True; } }
+                when Associative { for .pairs -> $p { register-arg($p); } }
+                when Positional { for .list -> $p { register-arg($p); } }
+                default { %e{$_} = True; }
+            }
+        }
+
+        for @args {
+            register-arg($_);
+        }
+        self.bless(*, :elems(%e));
+    }
+
+    submethod BUILD (:%!elems) { }
+
+    # Coercions to and from
+    method postcircumfix:<( )> ($s --> Set) { to-set($s) }
+    multi to-set (Set $set --> Set) { $set }
+    multi to-set (KeySet $set --> Set) { Set.new: $set }
+    multi to-set (Bag $bag --> Set) { Set.new: $bag }
+    multi to-set (KeyBag $bag --> Set) { Set.new: $bag }
+    multi to-set (@elems --> Set) { Set.new: @elems }
+    multi to-set ([*@elems] --> Set) { Set.new: @elems }
+    multi to-set (%elems --> Set) { Set.new: %elems.keys }
+    multi to-set ($elem --> Set) { die "Cannot coerce $elem.perl() to a Set; use set($elem.perl()) to create a one-element set" }
+
+    multi method Str(Any:D $ : --> Str) { "set(< %!elems.keys() >)" }
+    multi method gist(Any:D $ : --> Str) { "set({ %!elems.keys».gist.join(', ') })"
+    }
+    multi method perl(Any:D $ : --> Str) { 'set(' ~ join(', ', map { .perl }, %!elems.keys) ~ ')' }
+
+    method iterator() { %!elems.keys.iterator }
+    method list() { %!elems.keys }
+    method pick($count = 1) { %!elems.keys.pick($count) }
+    method roll($count = 1) { %!elems.keys.roll($count) }
+
+    # TODO: WHICH will require the capability for >1 pointer in ObjAt
+}
+
+sub set(*@args) {
+    Set.new(@args);
+}

src/core/stubs.pm

@@ -5,7 +5,8 @@
 # in the end.
 my class Whatever { ... }
 my class Bag is Iterable does Associative { }
-my class Set is Iterable does Associative { }
+my class KeyBag is Iterable does Associative { }
+my class KeySet is Iterable does Associative { }
 my class KeyHash is Iterable does Associative { }
 my class Seq is List does Positional { }
 my class Exception { ... }

tools/build/Makefile.in

@@ -221,6 +221,7 @@ CORE_SOURCES = \
   src/core/Temporal.pm \
   src/core/EXPORTHOW.pm \
   src/core/Pod.pm \
+  src/core/Set.pm \
   src/core/ObjAt.pm \
   src/core/operators.pm \
   src/core/metaops.pm \