[project @ 2003-04-17 15:23:32 by simonpj]

[ghc-hetmet.git] / ghc / compiler / typecheck / TcSplice.lhs

diff --git a/ghc/compiler/typecheck/TcSplice.lhs b/ghc/compiler/typecheck/TcSplice.lhs
index ba6891d..6a2c4d7 100644 (file)
--- a/ghc/compiler/typecheck/TcSplice.lhs
+++ b/ghc/compiler/typecheck/TcSplice.lhs
@@ -16,23 +16,25 @@ import TcRnDriver   ( importSupportingDecls, tcTopSrcDecls )
 import qualified Language.Haskell.THSyntax as Meta
 
 import HscTypes                ( HscEnv(..), GhciMode(..), PersistentCompilerState(..), unQualInScope )
-import HsSyn           ( HsBracket(..) )
+import HsSyn           ( HsBracket(..), HsExpr(..) )
 import Convert         ( convertToHsExpr, convertToHsDecls )
 import RnExpr          ( rnExpr )
 import RdrHsSyn                ( RdrNameHsExpr, RdrNameHsDecl )
 import RnHsSyn         ( RenamedHsExpr )
-import TcExpr          ( tcMonoExpr )
+import TcExpr          ( tcCheckRho )
 import TcHsSyn         ( TcExpr, TypecheckedHsExpr, mkHsLet, zonkTopExpr )
-import TcSimplify      ( tcSimplifyTop )
+import TcSimplify      ( tcSimplifyTop, tcSimplifyBracket )
+import TcUnify         ( unifyTauTy )
 import TcType          ( TcType, openTypeKind, mkAppTy )
-import TcEnv           ( spliceOK, tcMetaTy )
+import TcEnv           ( spliceOK, tcMetaTy, tcWithTempInstEnv, bracketOK )
 import TcRnTypes       ( TopEnv(..) )
-import TcMType         ( newTyVarTy, zapToType )
+import TcMType         ( newTyVarTy, zapToType, UserTypeCtxt(ExprSigCtxt) )
+import TcMonoType      ( tcHsSigType )
 import Name            ( Name )
 import TcRnMonad
 
 import TysWiredIn      ( mkListTy )
-import DsMeta          ( exprTyConName, declTyConName, decTyConName, qTyConName )
+import DsMeta          ( exprTyConName, declTyConName, typeTyConName, decTyConName, qTyConName )
 import ErrUtils (Message)
 import Outputable
 import Panic           ( showException )
@@ -63,20 +65,55 @@ tcSpliceDecls e     = pprPanic "Cant do tcSpliceDecls without GHCi" (ppr e)
 
 %************************************************************************
 %*                                                                     *
-\subsection{Splicing an expression}
+\subsection{Quoting an expression}
 %*                                                                     *
 %************************************************************************
 
 \begin{code}
-tcBracket :: HsBracket Name -> TcM TcType
-tcBracket (ExpBr expr) 
-  = newTyVarTy openTypeKind            `thenM` \ any_ty ->
-    tcMonoExpr expr any_ty             `thenM_`
+tcBracket :: HsBracket Name -> TcType -> TcM TcExpr
+tcBracket brack res_ty
+  = getStage                           `thenM` \ level ->
+    case bracketOK level of {
+       Nothing         -> failWithTc (illegalBracket level) ;
+       Just next_level ->
+
+       -- Typecheck expr to make sure it is valid,
+       -- but throw away the results.  We'll type check
+       -- it again when we actually use it.
+    newMutVar []                       `thenM` \ pending_splices ->
+    getLIEVar                          `thenM` \ lie_var ->
+
+    setStage (Brack next_level pending_splices lie_var) (
+       getLIE (tc_bracket brack)
+    )                                  `thenM` \ (meta_ty, lie) ->
+    tcSimplifyBracket lie              `thenM_`  
+
+    unifyTauTy res_ty meta_ty          `thenM_`
+
+       -- Return the original expression, not the type-decorated one
+    readMutVar pending_splices         `thenM` \ pendings ->
+    returnM (HsBracketOut brack pendings)
+    }
+
+tc_bracket :: HsBracket Name -> TcM TcType
+tc_bracket (ExpBr expr) 
+  = newTyVarTy openTypeKind    `thenM` \ any_ty ->
+    tcCheckRho expr any_ty     `thenM_`
     tcMetaTy exprTyConName
        -- Result type is Expr (= Q Exp)
 
-tcBracket (DecBr decls)
-  = tcTopSrcDecls decls                        `thenM_`
+tc_bracket (TypBr typ) 
+  = tcHsSigType ExprSigCtxt typ                `thenM_`
+    tcMetaTy typeTyConName
+       -- Result type is Type (= Q Typ)
+
+tc_bracket (DecBr decls)
+  = tcWithTempInstEnv (tcTopSrcDecls decls)    `thenM_`
+       -- Typecheck the declarations, dicarding any side effects
+       -- on the instance environment (which is in a mutable variable)
+       -- and the extended environment.  We'll get all that stuff
+       -- later, when we splice it in
+
     tcMetaTy decTyConName              `thenM` \ decl_ty ->
     tcMetaTy qTyConName                        `thenM` \ q_ty ->
     returnM (mkAppTy q_ty (mkListTy decl_ty))
@@ -111,7 +148,7 @@ tcSpliceExpr name expr res_ty
     tcMetaTy exprTyConName                     `thenM` \ meta_exp_ty ->
     setStage (Splice next_level) (
        setLIEVar lie_var          $
-       tcMonoExpr expr meta_exp_ty
+       tcCheckRho expr meta_exp_ty
     )                                          `thenM` \ expr' ->
 
        -- Write the pending splice into the bucket
@@ -125,7 +162,7 @@ tcSpliceExpr name expr res_ty
 -- Note that we do not decrement the level (to -1) before 
 -- typechecking the expression.  For example:
 --     f x = $( ...$(g 3) ... )
--- The recursive call to tcMonoExpr will simply expand the 
+-- The recursive call to tcCheckRho will simply expand the 
 -- inner escape before dealing with the outer one
 
 tcTopSplice expr res_ty
@@ -151,10 +188,12 @@ tcTopSplice expr res_ty
     initRn SourceMode (rnExpr expr2)           `thenM` \ (exp3, fvs) ->
     importSupportingDecls fvs                  `thenM` \ env ->
 
-    setGblEnv env (tcMonoExpr exp3 res_ty)
+    setGblEnv env (tcCheckRho exp3 res_ty)
 
 
 tcTopSpliceExpr :: RenamedHsExpr -> TcType -> TcM TypecheckedHsExpr
+-- Type check an expression that is the body of a top-level splice
+--   (the caller will compile and run it)
 tcTopSpliceExpr expr meta_ty
   = checkNoErrs $      -- checkNoErrs: must not try to run the thing
                        --              if the type checker fails!
@@ -162,7 +201,7 @@ tcTopSpliceExpr expr meta_ty
     setStage topSpliceStage $
 
        -- Typecheck the expression
-    getLIE (tcMonoExpr expr meta_ty)   `thenM` \ (expr', lie) ->
+    getLIE (tcCheckRho expr meta_ty)   `thenM` \ (expr', lie) ->
 
        -- Solve the constraints
     tcSimplifyTop lie                  `thenM` \ const_binds ->
@@ -362,6 +401,9 @@ showSplice what before after
                                    text "======>",
                                    nest 2 after])])
 
+illegalBracket level
+  = ptext SLIT("Illegal bracket at level") <+> ppr level
+
 illegalSplice level
   = ptext SLIT("Illegal splice at level") <+> ppr level