diff options
| author | simonpj@microsoft.com <unknown> | 2010-12-10 08:41:16 +0000 |
|---|---|---|
| committer | simonpj@microsoft.com <unknown> | 2010-12-10 08:41:16 +0000 |
| commit | b32e8c32b529411536612662d61f5445cee456db (patch) | |
| tree | e9a076a5a41840123abcd60ab7c26ee6c346ac79 /compiler | |
| parent | 29c2794f358b1175f5402d81bb84fd26a4d39019 (diff) | |
| download | haskell-b32e8c32b529411536612662d61f5445cee456db.tar.gz | |
Comments only
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/specialise/Specialise.lhs | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/compiler/specialise/Specialise.lhs b/compiler/specialise/Specialise.lhs index f6f85a1140..0613aa3264 100644 --- a/compiler/specialise/Specialise.lhs +++ b/compiler/specialise/Specialise.lhs @@ -1174,16 +1174,22 @@ Note [Specialisation of dictionary functions] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is a nasty example that bit us badly: see Trac #3591 + class Eq a => C a + instance Eq [a] => C [a] + +--------------- + dfun :: Eq [a] -> C [a] dfun a d = MkD a d (meth d) - d4 = <blah> - d2 = dfun T d4 - d1 = $p1 d2 - d3 = dfun T d1 + + d4 :: Eq [T] = <blah> + d2 :: C [T] = dfun T d4 + d1 :: Eq [T] = $p1 d2 + d3 :: C [T] = dfun T d1 None of these definitions is recursive. What happened was that we generated a specialisation: - RULE forall d. dfun T d = dT + RULE forall d. dfun T d = dT :: C [T] dT = (MkD a d (meth d)) [T/a, d1/d] = MkD T d1 (meth d1) |