#11736: Allow unsaturated uses of unlifted types in Core -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: feature | Status: new request | Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently Core Lint checks for unsaturated uses of unlifted types in . These are easily produced in the new type-indexed `Typeable` scheme. For instance, consider solving for `Typeable # (Array# Int)`: * We decompose the application into wanteds `Typeable (* -> #) Array#` and `Typeable * Int` * We construct dictionaries for both, giving us a term `typeRepArray# :: TypeRep (* -> #) Array#` While nothing seems to blow up with this patch, {{{#!patch diff --git a/compiler/coreSyn/CoreLint.hs b/compiler/coreSyn/CoreLint.hs index 99625c9..2c401de 100644 --- a/compiler/coreSyn/CoreLint.hs +++ b/compiler/coreSyn/CoreLint.hs @@ -1040,7 +1040,7 @@ lintType ty@(TyConApp tc tys) = lintType ty' -- Expand type synonyms, so that we do not bogusly complain -- about un-saturated type synonyms - | isUnliftedTyCon tc || isTypeSynonymTyCon tc || isTypeFamilyTyCon tc + | isTypeSynonymTyCon tc || isTypeFamilyTyCon tc -- Also type synonyms and type families , length tys < tyConArity tc = failWithL (hang (text "Un-saturated type application") 2 (ppr ty)) }}} I otherwise have no reason to believe that this is safe. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11736 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler