\section[TcGRHSs]{Typecheck guarded right-hand-sides}
\begin{code}
-#include "HsVersions.h"
-
module TcGRHSs ( tcGRHSsAndBinds ) where
-IMP_Ubiq(){-uitous-}
-IMPORT_DELOOPER(TcLoop) -- for paranoia checking
+#include "HsVersions.h"
-import HsSyn ( GRHSsAndBinds(..), GRHS(..),
- HsExpr, HsBinds(..), InPat, OutPat, Bind, Sig, Fake )
-import RnHsSyn ( SYN_IE(RenamedGRHSsAndBinds), SYN_IE(RenamedGRHS) )
-import TcHsSyn ( SYN_IE(TcGRHSsAndBinds), SYN_IE(TcGRHS), TcIdOcc(..) )
+import HsSyn ( HsBinds(..), GRHSsAndBinds(..), GRHS(..), DoOrListComp(..) )
+import RnHsSyn ( RenamedGRHSsAndBinds, RenamedGRHS )
+import TcHsSyn ( TcGRHSsAndBinds, TcGRHS )
import TcMonad
-import Inst ( Inst, SYN_IE(LIE), plusLIE )
+import Inst ( Inst, LIE, plusLIE )
import TcBinds ( tcBindsAndThen )
-import TcExpr ( tcExpr )
-import TcType ( SYN_IE(TcType) )
-import Unify ( unifyTauTy )
+import TcExpr ( tcExpr, tcStmt )
+import TcType ( TcType, newTyVarTy )
+import TcEnv ( TcIdOcc(..) )
import TysWiredIn ( boolTy )
\end{code}
\begin{code}
-tcGRHSs :: [RenamedGRHS] -> TcM s ([TcGRHS s], LIE s, TcType s)
-
-tcGRHSs [grhs]
- = tcGRHS grhs `thenTc` \ (grhs', lie, ty) ->
- returnTc ([grhs'], lie, ty)
+tcGRHSs :: TcType s -> [RenamedGRHS] -> TcM s ([TcGRHS s], LIE s)
-tcGRHSs (grhs:grhss)
- = tcGRHS grhs `thenTc` \ (grhs', lie1, ty1) ->
- tcGRHSs grhss `thenTc` \ (grhss', lie2, ty2) ->
- unifyTauTy ty1 ty2 `thenTc_`
- returnTc (grhs' : grhss', lie1 `plusLIE` lie2, ty1)
+tcGRHSs expected_ty [grhs]
+ = tcGRHS expected_ty grhs `thenTc` \ (grhs', lie) ->
+ returnTc ([grhs'], lie)
+tcGRHSs expected_ty (grhs:grhss)
+ = tcGRHS expected_ty grhs `thenTc` \ (grhs', lie1) ->
+ tcGRHSs expected_ty grhss `thenTc` \ (grhss', lie2) ->
+ returnTc (grhs' : grhss', lie1 `plusLIE` lie2)
-tcGRHS (OtherwiseGRHS expr locn)
- = tcAddSrcLoc locn $
- tcExpr expr `thenTc` \ (expr, lie, ty) ->
- returnTc (OtherwiseGRHS expr locn, lie, ty)
-
-tcGRHS (GRHS guard expr locn)
+tcGRHS expected_ty (GRHS guard expr locn)
= tcAddSrcLoc locn $
- tcExpr guard `thenTc` \ (guard2, guard_lie, guard_ty) ->
- unifyTauTy boolTy guard_ty `thenTc_`
- tcExpr expr `thenTc` \ (expr2, expr_lie, expr_ty) ->
- returnTc (GRHS guard2 expr2 locn, plusLIE guard_lie expr_lie, expr_ty)
+ tcStmts guard `thenTc` \ ((guard', expr'), lie) ->
+ returnTc (GRHS guard' expr' locn, lie)
+ where
+ tcStmts [] = tcExpr expr expected_ty `thenTc` \ (expr2, expr_lie) ->
+ returnTc (([], expr2), expr_lie)
+ tcStmts (stmt:stmts) = tcStmt tcExpr Guard (\x->x) combine stmt $
+ tcStmts stmts
+
+ combine stmt _ (stmts, expr) = (stmt:stmts, expr)
\end{code}
pieces.
\begin{code}
-tcGRHSsAndBinds :: RenamedGRHSsAndBinds
- -> TcM s (TcGRHSsAndBinds s, LIE s, TcType s)
+tcGRHSsAndBinds :: TcType s -- Expected type of RHSs
+ -> RenamedGRHSsAndBinds
+ -> TcM s (TcGRHSsAndBinds s, LIE s)
+
+-- Shortcut for common case
+tcGRHSsAndBinds expected_ty (GRHSsAndBindsIn grhss EmptyBinds)
+ = tcGRHSs expected_ty grhss `thenTc` \ (grhss', lie) ->
+ returnTc (GRHSsAndBindsOut grhss' EmptyBinds expected_ty, lie)
-tcGRHSsAndBinds (GRHSsAndBindsIn grhss binds)
+tcGRHSsAndBinds expected_ty (GRHSsAndBindsIn grhss binds)
= tcBindsAndThen
combiner binds
- (tcGRHSs grhss `thenTc` \ (grhss', lie, ty) ->
- returnTc (GRHSsAndBindsOut grhss' EmptyBinds ty, lie, ty)
- )
+ (tcGRHSs expected_ty grhss)
where
- combiner binds1 (GRHSsAndBindsOut grhss binds2 ty)
- = GRHSsAndBindsOut grhss (binds1 `ThenBinds` binds2) ty
+ combiner is_rec binds grhss
+ = GRHSsAndBindsOut grhss (MonoBind binds [] is_rec) expected_ty
\end{code}