diff options
| -rw-r--r-- | compiler/typecheck/TcRnDriver.lhs | 43 |
1 files changed, 29 insertions, 14 deletions
diff --git a/compiler/typecheck/TcRnDriver.lhs b/compiler/typecheck/TcRnDriver.lhs index 4f4b16600c..cfd96e3fb8 100644 --- a/compiler/typecheck/TcRnDriver.lhs +++ b/compiler/typecheck/TcRnDriver.lhs @@ -1575,27 +1575,42 @@ tcRnType :: HscEnv -> IO (Messages, Maybe (Type, Kind)) tcRnType hsc_env ictxt normalise rdr_type = initTcPrintErrors hsc_env iNTERACTIVE $ - setInteractiveContext hsc_env ictxt $ do { - - (rn_type, _fvs) <- rnLHsType GHCiCtx rdr_type ; - failIfErrsM ; + setInteractiveContext hsc_env ictxt $ + setXOptM Opt_PolyKinds $ -- See Note [Kind-generalise in tcRnType] + do { (rn_type, _fvs) <- rnLHsType GHCiCtx rdr_type + ; failIfErrsM -- Now kind-check the type -- It can have any rank or kind - ty <- tcHsSigType GhciCtxt rn_type ; + ; ty <- tcHsSigType GhciCtxt rn_type ; - ty' <- if normalise - then do { fam_envs <- tcGetFamInstEnvs - ; return (snd (normaliseType fam_envs ty)) } - -- normaliseType returns a coercion - -- which we discard - else return ty ; - - return (ty', typeKind ty) - } + ; ty' <- if normalise + then do { fam_envs <- tcGetFamInstEnvs + ; return (snd (normaliseType fam_envs ty)) } + -- normaliseType returns a coercion + -- which we discard + else return ty ; + ; return (ty', typeKind ty) } \end{code} +Note [Kind-generalise in tcRnType] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +We switch on PolyKinds when kind-checking a user type, so that we will +kind-generalise the type. This gives the right default behaviour at +the GHCi prompt, where if you say ":k T", and T has a polymorphic +kind, you'd like to see that polymorphism. Of course. If T isn't +kind-polymorphic you won't get anything unexpected, but the apparent +*loss* of polymorphism, for types that you konw are polymorphic, is +quite surprising. See Trac #7688 for a discussion. + + +%************************************************************************ +%* * + tcRnDeclsi +%* * +%************************************************************************ + tcRnDeclsi exists to allow class, data, and other declarations in GHCi. \begin{code} |