From c79947821b62c16f0a5a21fb5ec935c1dba00aae Mon Sep 17 00:00:00 2001 From: Adam Chlipala Date: Thu, 6 Aug 2009 15:23:04 -0400 Subject: Fix type class resolution infinite loop, discovered while meeting with Ezra --- src/elab_env.sml | 43 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-) (limited to 'src/elab_env.sml') diff --git a/src/elab_env.sml b/src/elab_env.sml index c7dfc0b1..1bd4e059 100644 --- a/src/elab_env.sml +++ b/src/elab_env.sml @@ -500,6 +500,47 @@ fun unifyKinds (k1, k2) = | (KFun (_, k1), KFun (_, k2)) => unifyKinds (k1, k2) | _ => raise Unify +fun eqCons (c1, c2) = + case (#1 c1, #1 c2) of + (CUnif (_, _, _, ref (SOME c1)), _) => eqCons (c1, c2) + | (_, CUnif (_, _, _, ref (SOME c2))) => eqCons (c1, c2) + + | (CRel n1, CRel n2) => if n1 = n2 then () else raise Unify + + | (TFun (d1, r1), TFun (d2, r2)) => (eqCons (d1, d2); eqCons (r1, r2)) + | (TCFun (_, _, k1, r1), TCFun (_, _, k2, r2)) => (unifyKinds (k1, k2); eqCons (r1, r2)) + | (TRecord c1, TRecord c2) => eqCons (c1, c2) + | (TDisjoint (a1, b1, c1), TDisjoint (a2, b2, c2)) => + (eqCons (a1, a2); eqCons (b1, b2); eqCons (c1, c2)) + + | (CNamed n1, CNamed n2) => if n1 = n2 then () else raise Unify + | (CModProj (n1, ms1, x1), CModProj (n2, ms2, x2)) => + if n1 = n2 andalso ms1 = ms2 andalso x1 = x2 then () else raise Unify + | (CApp (f1, x1), CApp (f2, x2)) => (eqCons (f1, f2); eqCons (x1, x2)) + | (CAbs (_, k1, b1), CAbs (_, k2, b2)) => (unifyKinds (k1, k2); eqCons (b1, b2)) + + | (CKAbs (_, b1), CKAbs (_, b2)) => eqCons (b1, b2) + | (CKApp (c1, k1), CKApp (c2, k2)) => (eqCons (c1, c2); unifyKinds (k1, k2)) + | (TKFun (_, c1), TKFun (_, c2)) => eqCons (c1, c2) + + | (CName s1, CName s2) => if s1 = s2 then () else raise Unify + + | (CRecord (k1, xcs1), CRecord (k2, xcs2)) => + (unifyKinds (k1, k2); + ListPair.appEq (fn ((x1, c1), (x2, c2)) => (eqCons (x1, x2); eqCons (c1, c2))) (xcs1, xcs2) + handle ListPair.UnequalLengths => raise Unify) + | (CConcat (f1, x1), CConcat (f2, x2)) => (eqCons (f1, f2); eqCons (x1, x2)) + | (CMap (d1, r1), CMap (d2, r2)) => (unifyKinds (d1, d2); unifyKinds (r1, r2)) + + | (CUnit, CUnit) => () + + | (CTuple cs1, CTuple cs2) => (ListPair.appEq (eqCons) (cs1, cs2) + handle ListPair.UnequalLengths => raise Unify) + | (CProj (c1, n1), CProj (c2, n2)) => (eqCons (c1, c2); + if n1 = n2 then () else raise Unify) + + | _ => raise Unify + fun unifyCons rs = let fun unify d (c1, c2) = @@ -524,7 +565,7 @@ fun unifyCons rs = in case !r of NONE => r := SOME c1 - | SOME c2 => unify d (c1, c2) + | SOME c2 => eqCons (c1, c2) end | (TFun (d1, r1), TFun (d2, r2)) => (unify d (d1, d2); unify d (r1, r2)) -- cgit v1.2.3