[commit: ghc] master: Code cleaning (9e238da)

[David Terei]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/9e238da6f0defe6397eb67603af868125fe5398f

>---------------------------------------------------------------

commit 9e238da6f0defe6397eb67603af868125fe5398f
Author: David Terei <davidterei at gmail.com>
Date:   Wed Jan 25 23:49:54 2012 -0800

    Code cleaning

>---------------------------------------------------------------

 compiler/main/HscMain.hs          |   47 +++++++++++-------------------------
 compiler/typecheck/TcRnDriver.lhs |    2 -
 2 files changed, 15 insertions(+), 34 deletions(-)

diff --git a/compiler/main/HscMain.hs b/compiler/main/HscMain.hs
index 6f670e7..e06e6fa 100644
--- a/compiler/main/HscMain.hs
+++ b/compiler/main/HscMain.hs
@@ -1351,31 +1351,12 @@ myCoreToStg dflags this_mod prepd_binds = do
 %********************************************************************* -}
 
 {-
-When the UnlinkedBCOExpr is linked you get an HValue of type
-        IO [HValue]
-When you run it you get a list of HValues that should be
-the same length as the list of names; add them to the ClosureEnv.
+When the UnlinkedBCOExpr is linked you get an HValue of type *IO [HValue]* When
+you run it you get a list of HValues that should be the same length as the list
+of names; add them to the ClosureEnv.
 
-A naked expression returns a singleton Name [it].
-
-        What you type                   The IO [HValue] that hscStmt returns
-        -------------                   ------------------------------------
-        let pat = expr          ==>     let pat = expr in return [coerce HVal x, coerce HVal y, ...]
-                                        bindings: [x,y,...]
-
-        pat <- expr             ==>     expr >>= \ pat -> return [coerce HVal x, coerce HVal y, ...]
-                                        bindings: [x,y,...]
-
-        expr (of IO type)       ==>     expr >>= \ v -> return [v]
-          [NB: result not printed]      bindings: [it]
-
-
-        expr (of non-IO type,
-          result showable)      ==>     let v = expr in print v >> return [v]
-                                        bindings: [it]
-
-        expr (of non-IO type,
-          result not showable)  ==>     error
+A naked expression returns a singleton Name [it]. The stmt is lifted into the
+IO monad as explained in Note [Interactively-bound Ids in GHCi] in TcRnDriver
 -}
 
 #ifdef GHCI
@@ -1400,21 +1381,23 @@ hscStmtWithLocation hsc_env stmt source linenumber = runHsc hsc_env $ do
     case maybe_stmt of
         Nothing -> return Nothing
 
-        -- The real stuff
         Just parsed_stmt -> do
-             -- Rename and typecheck it
-            let icontext = hsc_IC hsc_env
-            (ids, tc_expr) <- ioMsgMaybe $
-                                  tcRnStmt hsc_env icontext parsed_stmt
+            let icntxt   = hsc_IC hsc_env
+                rdr_env  = ic_rn_gbl_env icntxt
+                type_env = mkTypeEnvWithImplicits (ic_tythings icntxt)
+                src_span = srcLocSpan interactiveSrcLoc
+
+            -- Rename and typecheck it
+            -- Here we lift the stmt into the IO monad, see Note
+            -- [Interactively-bound Ids in GHCi] in TcRnDriver
+            (ids, tc_expr) <- ioMsgMaybe $ tcRnStmt hsc_env icntxt parsed_stmt
+
             -- Desugar it
-            let rdr_env  = ic_rn_gbl_env icontext
-                type_env = mkTypeEnvWithImplicits (ic_tythings icontext)
             ds_expr <- ioMsgMaybe $
                            deSugarExpr hsc_env iNTERACTIVE rdr_env type_env tc_expr
             handleWarnings
 
             -- Then code-gen, and link it
-            let src_span = srcLocSpan interactiveSrcLoc
             hsc_env <- getHscEnv
             hval    <- liftIO $ hscCompileCoreExpr hsc_env src_span ds_expr
             let hval_io = unsafeCoerce# hval :: IO [HValue]
diff --git a/compiler/typecheck/TcRnDriver.lhs b/compiler/typecheck/TcRnDriver.lhs
index 5d81de0..6f7e68a 100644
--- a/compiler/typecheck/TcRnDriver.lhs
+++ b/compiler/typecheck/TcRnDriver.lhs
@@ -1240,7 +1240,6 @@ The Ids bound by previous Stmts in GHCi are currently
      to look at them, and :info expects the things it looks up to have
      tidy types
 
-
 --------------------------------------------------------------------------
                 Typechecking Stmts in GHCi
 
@@ -1263,7 +1262,6 @@ Here is the grand plan, implemented in tcUserStmt
         expr (of non-IO type,
           result not showable)  ==>     error
 
-
 \begin{code}
 
 type PlanResult = ([Id], LHsExpr Id)