diff options
Diffstat (limited to 'src/elaborate.sml')
| -rw-r--r-- | src/elaborate.sml | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/src/elaborate.sml b/src/elaborate.sml index eccc4840..71842ec2 100644 --- a/src/elaborate.sml +++ b/src/elaborate.sml @@ -817,7 +817,24 @@ ("#2", p_summary env {fields = fs2, unifs = unifs2, others = others2})]*) val empty = (L'.CRecord (k, []), loc) - fun failure () = raise CUnify' (CRecordFailure (unsummarize s1, unsummarize s2)) + fun failure () = + let + val fs2 = #fields s2 + + fun findPointwise fs1 = + case fs1 of + [] => NONE + | (nm1, c1) :: fs1 => + case List.find (fn (nm2, _) => consEq env loc (nm1, nm2)) fs2 of + NONE => findPointwise fs1 + | SOME (_, c2) => + if consEq env loc (c1, c2) then + findPointwise fs1 + else + SOME (nm1, c1, c2) + in + raise CUnify' (CRecordFailure (unsummarize s1, unsummarize s2, findPointwise (#fields s1))) + end in (case (unifs1, fs1, others1, unifs2, fs2, others2) of (_, [], [], [], [], []) => |