Reorganisation of the source tree

[ghc-hetmet.git] / ghc / compiler / deSugar / DsGRHSs.lhs

diff --git a/ghc/compiler/deSugar/DsGRHSs.lhs b/ghc/compiler/deSugar/DsGRHSs.lhs
deleted file mode 100644 (file)
index eea61ba..0000000
--- a/ghc/compiler/deSugar/DsGRHSs.lhs
+++ /dev/null
@@ -1,128 +0,0 @@
-%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-%
-\section[DsGRHSs]{Matching guarded right-hand-sides (GRHSs)}
-
-\begin{code}
-module DsGRHSs ( dsGuarded, dsGRHSs ) where
-
-#include "HsVersions.h"
-
-import {-# SOURCE #-} DsExpr  ( dsLExpr, dsLocalBinds )
-import {-# SOURCE #-} Match   ( matchSinglePat )
-
-import HsSyn           ( Stmt(..), HsExpr(..), GRHSs(..), GRHS(..), 
-                         LHsExpr, HsMatchContext(..), Pat(..) )
-import CoreSyn         ( CoreExpr )
-import Var             ( Id )
-import Type            ( Type )
-
-import DsMonad
-import DsUtils
-import Unique          ( Uniquable(..) )
-import PrelInfo                ( nON_EXHAUSTIVE_GUARDS_ERROR_ID )
-import TysWiredIn      ( trueDataConId )
-import PrelNames       ( otherwiseIdKey, hasKey )
-import Name            ( Name )
-import SrcLoc          ( unLoc, Located(..) )
-\end{code}
-
-@dsGuarded@ is used for both @case@ expressions and pattern bindings.
-It desugars:
-\begin{verbatim}
-       | g1 -> e1
-       ...
-       | gn -> en
-       where binds
-\end{verbatim}
-producing an expression with a runtime error in the corner if
-necessary.  The type argument gives the type of the @ei@.
-
-\begin{code}
-dsGuarded :: GRHSs Id -> Type -> DsM CoreExpr
-
-dsGuarded grhss rhs_ty
-  = dsGRHSs PatBindRhs [] grhss rhs_ty                                 `thenDs` \ match_result ->
-    mkErrorAppDs nON_EXHAUSTIVE_GUARDS_ERROR_ID rhs_ty ""      `thenDs` \ error_expr ->
-    extractMatchResult match_result error_expr
-\end{code}
-
-In contrast, @dsGRHSs@ produces a @MatchResult@.
-
-\begin{code}
-dsGRHSs :: HsMatchContext Name -> [Pat Id]     -- These are to build a MatchContext from
-       -> GRHSs Id                             -- Guarded RHSs
-       -> Type                                 -- Type of RHS
-       -> DsM MatchResult
-
-dsGRHSs hs_ctx pats (GRHSs grhss binds) rhs_ty
-  = mappM (dsGRHS hs_ctx pats rhs_ty) grhss    `thenDs` \ match_results ->
-    let 
-       match_result1 = foldr1 combineMatchResults match_results
-       match_result2 = adjustMatchResultDs (dsLocalBinds binds) match_result1
-               -- NB: nested dsLet inside matchResult
-    in
-    returnDs match_result2
-
-dsGRHS hs_ctx pats rhs_ty (L loc (GRHS guards rhs))
-  = matchGuards (map unLoc guards) hs_ctx rhs rhs_ty
-\end{code}
-
-
-%************************************************************************
-%*                                                                     *
-%*  matchGuard : make a MatchResult from a guarded RHS                 *
-%*                                                                     *
-%************************************************************************
-
-\begin{code}
-matchGuards :: [Stmt Id]               -- Guard
-            -> HsMatchContext Name     -- Context
-           -> LHsExpr Id               -- RHS
-           -> Type                     -- Type of RHS of guard
-           -> DsM MatchResult
-
--- See comments with HsExpr.Stmt re what an ExprStmt means
--- Here we must be in a guard context (not do-expression, nor list-comp)       
-
-matchGuards [] ctx rhs rhs_ty
-  = do { core_rhs <- dsLExpr rhs
-       ; return (cantFailMatchResult core_rhs) }
-
-       -- ExprStmts must be guards
-       -- Turn an "otherwise" guard is a no-op.  This ensures that 
-       -- you don't get a "non-exhaustive eqns" message when the guards 
-       -- finish in "otherwise".
-       -- NB:  The success of this clause depends on the typechecker not
-       --      wrapping the 'otherwise' in empty HsTyApp or HsCoerce constructors
-       --      If it does, you'll get bogus overlap warnings
-matchGuards (ExprStmt (L _ (HsVar v)) _ _ : stmts) ctx rhs rhs_ty
-  |  v `hasKey` otherwiseIdKey
-  || v `hasKey` getUnique trueDataConId        
-       -- trueDataConId doesn't have the same unique as trueDataCon
-  = matchGuards stmts ctx rhs rhs_ty
-
-matchGuards (ExprStmt expr _ _ : stmts) ctx rhs rhs_ty
-  = matchGuards stmts ctx rhs rhs_ty   `thenDs` \ match_result ->
-    dsLExpr expr                       `thenDs` \ pred_expr ->
-    returnDs (mkGuardedMatchResult pred_expr match_result)
-
-matchGuards (LetStmt binds : stmts) ctx rhs rhs_ty
-  = matchGuards stmts ctx rhs rhs_ty   `thenDs` \ match_result ->
-    returnDs (adjustMatchResultDs (dsLocalBinds binds) match_result)
-       -- NB the dsLet occurs inside the match_result
-       -- Reason: dsLet takes the body expression as its argument
-       --         so we can't desugar the bindings without the
-       --         body expression in hand
-
-matchGuards (BindStmt pat bind_rhs _ _ : stmts) ctx rhs rhs_ty
-  = matchGuards stmts ctx rhs rhs_ty   `thenDs` \ match_result ->
-    dsLExpr bind_rhs                   `thenDs` \ core_rhs ->
-    matchSinglePat core_rhs ctx pat rhs_ty match_result
-\end{code}
-
-Should {\em fail} if @e@ returns @D@
-\begin{verbatim}
-f x | p <- e', let C y# = e, f y# = r1
-    | otherwise         = r2 
-\end{verbatim}