Monadify typecheck/TcInstDcls: use do, return and standard monad functions

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

diff --git a/compiler/typecheck/TcRnDriver.lhs b/compiler/typecheck/TcRnDriver.lhs
index c744c15..a646125 100644 (file)
--- a/compiler/typecheck/TcRnDriver.lhs
+++ b/compiler/typecheck/TcRnDriver.lhs
@@ -320,8 +320,8 @@ tcRnExtCore hsc_env (HsExtCore this_mod decls src_binds)
 
        mod_guts = ModGuts {    mg_module    = this_mod,
                                mg_boot      = False,
-                               mg_usages    = [],              -- ToDo: compute usage
-                               mg_dir_imps  = [],              -- ??
+                               mg_used_names = emptyNameSet, -- ToDo: compute usage
+                               mg_dir_imps  = emptyModuleEnv, -- ??
                                mg_deps      = noDependencies,  -- ??
                                mg_exports   = my_exports,
                                mg_types     = final_type_env,
@@ -899,16 +899,7 @@ tcRnStmt hsc_env ictxt rdr_stmt
     mappM bad_unboxed (filter (isUnLiftedType . idType) zonked_ids) ;
 
     traceTc (text "tcs 1") ;
-    let {      -- (a) Make all the bound ids "global" ids, now that
-               --     they're notionally top-level bindings.  This is
-               --     important: otherwise when we come to compile an expression
-               --     using these ids later, the byte code generator will consider
-               --     the occurrences to be free rather than global.
-               -- 
-               -- (b) Tidy their types; this is important, because :info may
-               --     ask to look at them, and :info expects the things it looks
-               --     up to have tidy types
-       global_ids = map globaliseAndTidy zonked_ids ;
+    let { global_ids = map globaliseAndTidy zonked_ids } ;
     
 {- ---------------------------------------------
    At one stage I removed any shadowed bindings from the type_env;
@@ -928,7 +919,6 @@ tcRnStmt hsc_env ictxt rdr_stmt
    Hence this code is commented out
 
 -------------------------------------------------- -}
-    } ;
 
     dumpOptTcRn Opt_D_dump_tc 
        (vcat [text "Bound Ids" <+> pprWithCommas ppr global_ids,
@@ -941,13 +931,35 @@ tcRnStmt hsc_env ictxt rdr_stmt
                                  nest 2 (ppr id <+> dcolon <+> ppr (idType id))])
 
 globaliseAndTidy :: Id -> Id
-globaliseAndTidy id
--- Give the Id a Global Name, and tidy its type
+globaliseAndTidy id    -- Note [Interactively-bound Ids in GHCi]
   = Id.setIdType (globaliseId VanillaGlobal id) tidy_type
   where
     tidy_type = tidyTopType (idType id)
 \end{code}
 
+Note [Interactively-bound Ids in GHCi]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The Ids bound by previous Stmts in Template Haskell are currently
+       a) GlobalIds
+       b) with an Internal Name (not External)
+       c) and a tidied type
+
+ (a) They must be GlobalIds (not LocalIds) otherwise when we come to
+     compile an expression using these ids later, the byte code
+     generator will consider the occurrences to be free rather than
+     global.
+
+ (b) They retain their Internal names becuase we don't have a suitable
+     Module to name them with.  We could revisit this choice.
+
+ (c) Their types are tidied.  This is important, because :info may ask
+     to look at them, and :info expects the things it looks up to have
+     tidy types
+       
+
+--------------------------------------------------------------------------
+               Typechecking Stmts in GHCi
+
 Here is the grand plan, implemented in tcUserStmt
 
        What you type                   The IO [HValue] that hscStmt returns
@@ -1044,10 +1056,9 @@ tcGhciStmts stmts
  = do { ioTyCon <- tcLookupTyCon ioTyConName ;
        ret_id  <- tcLookupId returnIOName ;            -- return @ IO
        let {
-           io_ty     = mkTyConApp ioTyCon [] ;
            ret_ty    = mkListTy unitTy ;
            io_ret_ty = mkTyConApp ioTyCon [ret_ty] ;
-           tc_io_stmts stmts = tcStmts DoExpr (tcDoStmt io_ty) stmts 
+           tc_io_stmts stmts = tcStmts DoExpr tcDoStmt stmts 
                                        (emptyRefinement, io_ret_ty) ;
 
            names = map unLoc (collectLStmtsBinders stmts) ;