Add infix C«(<)», infix C«⊂», infix C«⊄» to operators

Author: lizmat

doc/Language/operators.pod6

@@ -2247,6 +2247,41 @@ C<!(cont)>.
 
 C«∉» is codepoint U+220C (DOES NOT CONTAIN AS MEMBER).
 
+=head2 infix C«(<)», infix C«⊂»
+
+    multi sub infix:<(<)>($a,$b --> Bool:D)
+    multi sub infix:<⊂>($a,$b --> Bool:D)
+
+X<Subset of operator>.
+
+Returns C<True> if C<$a> is a B<strict subset> of C<$b>, i.e., that all the
+elements of C<$a> are elements of C<$b> but C<$a> is a smaller set than C<$b>.
+
+    =begin code
+    say (1,2,3) (<) (2,3,1); # OUTPUT: «False␤»
+    say (2,3) (<) (2,3,1); # OUTPUT: «True␤»
+    say 4 ⊂ (1,2,3); # OUTPUT: «False␤»
+    =end code
+
+C«⊂» is equivalent to C«(<)», at codepoint U+2282 (SUBSET OF).
+
+=head2 infix C«⊄»
+
+    multi sub infix:<⊄>($a,$b --> Bool:D)
+
+X<Not a subset of operator>.
+
+Returns C<True> if C<$a> is B<not> a C<strict subset> of C<$b>.  Equivalent to
+C«!(<)».
+
+    =begin code
+    say (1,2,3) ⊄ (2,3,1); # OUTPUT: «True␤»
+    say (2,3) ⊄ (2,3,1); # OUTPUT: «False␤»
+    say 4 !(<) (1,2,3); # OUTPUT: «True␤»
+    =end code
+
+C«⊄» is codepoint U+2284 (NOT A SUBSET OF).
+
 =head1 Tight AND precedence
 
 =head2 infix C«&&»
@@ -3216,30 +3251,6 @@ Alternate X<neither subset of nor equal to operator>, at codepoint U+2288
 
 Equivalent to C«!(<=)».
 
-=head3 infix (<)
-
-X<Subset of operator>.
-
-Returns C<True> if C<$a> is a B<strict subset> of C<$b>.
-
-=head3 infix ⊂
-
-Alternate X<subset of operator>, at codepoint U+2282 (SUBSET OF).
-
-Equivalent to L«(<)».
-
-=head3 infix !(<)
-
-X<Not a subset of operator>.
-
-Returns C<True> if C<$a> is a B<not a strict subset> of C<$b>.
-
-=head3 infix ⊄
-
-Alternate X<not a subset of operator>, at codepoint U+2284 (NOT A SUBSET OF).
-
-Equivalent to C«!(<)».
-
 =head3 infix (>=)
 
 X<Superset of or equal to operator>.