[project @ 2005-04-15 14:33:49 by simonpj]

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

diff --git a/ghc/compiler/typecheck/TcRnTypes.lhs b/ghc/compiler/typecheck/TcRnTypes.lhs
index a89ebf3..f9f9275 100644 (file)
--- a/ghc/compiler/typecheck/TcRnTypes.lhs
+++ b/ghc/compiler/typecheck/TcRnTypes.lhs
@@ -50,7 +50,7 @@ import HscTypes               ( FixityEnv,
 import Packages                ( PackageId )
 import Type            ( Type, TvSubstEnv, pprParendType, pprTyThingCategory )
 import TcType          ( TcTyVarSet, TcType, TcTauType, TcThetaType, SkolemInfo,
-                         TcPredType, TcKind, tcCmpPred, tcCmpType, tcCmpTypes )
+                         TcPredType, TcKind, tcCmpPred, tcCmpType, tcCmpTypes, pprSkolInfo )
 import InstEnv         ( DFunId, InstEnv )
 import IOEnv
 import RdrName         ( GlobalRdrEnv, LocalRdrEnv )
@@ -361,7 +361,8 @@ topSpliceStage = Splice (topLevel - 1)      -- Stage for the body of a top-level spli
 ---------------------------
 
 -- In arrow notation, a variable bound by a proc (or enclosed let/kappa)
--- is not in scope to the left of an arrow tail (-<).  For example
+-- is not in scope to the left of an arrow tail (-<) or the head of (|..|).
+-- For example
 --
 --     proc x -> (e1 -< e2)
 --
@@ -369,7 +370,7 @@ topSpliceStage = Splice (topLevel - 1)      -- Stage for the body of a top-level spli
 -- a bit complicated:
 --
 --     let x = 3 in
---     prox y -> (proc z -> e1) -< e2
+--     proc y -> (proc z -> e1) -< e2
 --
 -- Here, x and z are in scope in e1, but y is not.  Here's how we track this:
 --     a) Assign an "proc level" to each proc, being the number of
@@ -378,7 +379,8 @@ topSpliceStage = Splice (topLevel - 1)      -- Stage for the body of a top-level spli
 --        enclosing proc.
 --     c) Keep a list of out-of-scope procs.  When moving to the left of
 --        an arrow-tail, add the proc-level of the immediately enclosing
---        proc to the list.
+--        proc to the list, and increment the proc-level so that variables
+--        bound inside the expression are in scope.
 --     d) When looking up a variable, complain if its proc-level is in
 --        the banned list
 
@@ -670,10 +672,11 @@ data Inst
 
   | LitInst
        Name
-       HsOverLit       -- The literal from the occurrence site
-                       --      INVARIANT: never a rebindable-syntax literal
-                       --      Reason: tcSyntaxName does unification, and we
-                       --              don't want to deal with that during tcSimplify
+       (HsOverLit Name)        -- The literal from the occurrence site
+                               -- INVARIANT: never a rebindable-syntax literal
+                               -- Reason: tcSyntaxName does unification, and we
+                               --         don't want to deal with that during tcSimplify,
+                               --         when resolving LitInsts
        TcType          -- The type at which the literal is used
        InstLoc
 \end{code}
@@ -761,7 +764,7 @@ data InstOrigin
 
   | IPOccOrigin  (IPName Name) -- Occurrence of an implicit parameter
 
-  | LiteralOrigin HsOverLit    -- Occurrence of a literal
+  | LiteralOrigin (HsOverLit Name)     -- Occurrence of a literal
 
   | ArithSeqOrigin (ArithSeqInfo Name) -- [x..], [x..y] etc
   | PArrSeqOrigin  (ArithSeqInfo Name) -- [:x..y:] and [:x,y..z:]
@@ -779,8 +782,6 @@ data InstOrigin
 
 \begin{code}
 pprInstLoc :: InstLoc -> SDoc
-pprInstLoc (InstLoc (SigOrigin info) locn _) 
-  = text "arising from" <+> ppr info   -- I don't think this happens much, if at all
 pprInstLoc (InstLoc orig locn _)
   = hsep [text "arising from", pp_orig orig, text "at", ppr locn]
   where
@@ -791,11 +792,11 @@ pprInstLoc (InstLoc orig locn _)
     pp_orig (LiteralOrigin lit)         = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
     pp_orig (ArithSeqOrigin seq) = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
     pp_orig (PArrSeqOrigin seq)         = hsep [ptext SLIT("the parallel array sequence"), quotes (ppr seq)]
-    pp_orig InstSigOrigin       =  ptext SLIT("instantiating a type signature")
-    pp_orig InstScOrigin        =  ptext SLIT("the superclasses of an instance declaration")
+    pp_orig InstSigOrigin       = ptext SLIT("instantiating a type signature")
+    pp_orig InstScOrigin        = ptext SLIT("the superclasses of an instance declaration")
     pp_orig DerivOrigin                 = ptext SLIT("the 'deriving' clause of a data type declaration")
     pp_orig DefaultOrigin       = ptext SLIT("a 'default' declaration")
-    pp_orig DoOrigin            =  ptext SLIT("a do statement")
-    pp_orig ProcOrigin          =  ptext SLIT("a proc expression")
-    pp_orig (SigOrigin info)    = ppr info
+    pp_orig DoOrigin            = ptext SLIT("a do statement")
+    pp_orig ProcOrigin          = ptext SLIT("a proc expression")
+    pp_orig (SigOrigin info)    = pprSkolInfo info
 \end{code}