Implement missing equality on ADTs (enum variants)

Implement the missing case of the `==` operator for newly introduced
ADTs (enum variants), together with basic tests.

Co-authored-by: jneem <joeneeman@gmail.com>

core/src/eval/operation.rs

@@ -3126,7 +3126,12 @@ fn eq<C: Cache>(
  (Term::Str(s1), Term::Str(s2)) => Ok(EqResult::Bool(s1 == s2)),
  (Term::Lbl(l1), Term::Lbl(l2)) => Ok(EqResult::Bool(l1 == l2)),
  (Term::SealingKey(s1), Term::SealingKey(s2)) => Ok(EqResult::Bool(s1 == s2)),
- (Term::Enum(id1), Term::Enum(id2)) => Ok(EqResult::Bool(id1 == id2)),
+ (Term::Enum(id1), Term::Enum(id2)) => Ok(EqResult::Bool(id1.ident() == id2.ident())),
+ (Term::EnumVariant(id1, arg1), Term::EnumVariant(id2, arg2))
+ if id1.ident() == id2.ident() =>
+ {
+ Ok(gen_eqs(cache, std::iter::once((arg1, arg2)), env1, env2))
+ }
  (Term::Record(r1), Term::Record(r2)) => {
  let merge::split::SplitResult {
  left,

core/tests/integration/pass/core/eq.ncl

@@ -77,5 +77,11 @@ let {check, ..} = import "../lib/assert.ncl" in
  [[1,2,3,4], [1,2,3,4], [1,2,3,4], [1,2,3,4]]
  == false
  ),
+
+ # ADTs
+ 'Left..(1+1) == 'Left..(2),
+ 'Left..(1) != 'Left..(2),
+ 'Left..(2) != 'Right..(2),
+ 'Up..([1,2,3]) == 'Up..([0+1,1+1,2+1]),
 ]
 |> check