diff options
| author |  Adam Chlipala <adamc@hcoop.net> | 2009-03-26 15:54:04 -0400 |
|---|---|---|
| committer | Adam Chlipala <adamc@hcoop.net> | 2009-03-26 15:54:04 -0400 |
| commit | 024acc734f4a323883adb5e9a68f5f4f753e60cc (patch) | |
| tree | ddd45517e0df460b44d219633cdb5645f5d29bf8 /src/elab_env.sml | |
| parent | ea1046a80313fc7f22c97587bdffb3f90e91eb98 (diff) | |
Enforce termination of type class instances
Diffstat (limited to 'src/elab_env.sml')
| -rw-r--r-- | src/elab_env.sml | 39 |
1 files changed, 34 insertions, 5 deletions
diff --git a/src/elab_env.sml b/src/elab_env.sml index 9f64a8c2..de33ec56 100644 --- a/src/elab_env.sml +++ b/src/elab_env.sml @@ -182,6 +182,7 @@ fun compare x = fn () => String.compare (x1, x2))) end +structure CS = BinarySetFn(CK) structure CM = BinaryMapFn(CK) datatype class_key = @@ -697,8 +698,8 @@ fun rule_in c = case #1 c of TFun (hyp, c) => (case class_pair_in hyp of - NONE => NONE - | SOME p => clauses (c, p :: hyps)) + SOME (p as (_, CkRel _)) => clauses (c, p :: hyps) + | _ => NONE) | _ => case class_pair_in c of NONE => NONE @@ -730,6 +731,32 @@ fun rule_in c = | _ => quantifiers (c, 0) end +fun inclusion (classes : class CM.map, init, inclusions, f, e : exp) = + let + fun search (f, fs) = + if f = init then + NONE + else if CS.member (fs, f) then + SOME fs + else + let + val fs = CS.add (fs, f) + in + case CM.find (classes, f) of + NONE => SOME fs + | SOME {inclusions = fs', ...} => + CM.foldli (fn (f', _, fs) => + case fs of + NONE => NONE + | SOME fs => search (f', fs)) (SOME fs) fs' + end + in + case search (f, CS.empty) of + SOME _ => CM.insert (inclusions, f, e) + | NONE => (ErrorMsg.errorAt (#2 e) "Type class inclusion would create a cycle"; + inclusions) + end + fun pushENamedAs (env : env) x n t = let val classes = #classes env @@ -749,7 +776,7 @@ fun pushENamedAs (env : env) x n t = inclusions = #inclusions class} | Inclusion f' => {ground = #ground class, - inclusions = CM.insert (#inclusions class, f', e)} + inclusions = inclusion (classes, f, #inclusions class, f', e)} in CM.insert (classes, f, class) end @@ -1113,7 +1140,8 @@ fun enrichClasses env classes (m1, ms) sgn = inclusions = #inclusions class} | Inclusion f' => {ground = #ground class, - inclusions = CM.insert (#inclusions class, + inclusions = inclusion (classes, cn, + #inclusions class, globalizeN f', e)} in CM.insert (classes, cn, class) @@ -1146,7 +1174,8 @@ fun enrichClasses env classes (m1, ms) sgn = inclusions = #inclusions class} | Inclusion f' => {ground = #ground class, - inclusions = CM.insert (#inclusions class, + inclusions = inclusion (classes, cn, + #inclusions class, globalizeN f', e)} in CM.insert (classes, cn, class) |