[project @ 1996-03-19 08:58:34 by partain]

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

diff --git a/ghc/compiler/typecheck/TcPolyType.lhs b/ghc/compiler/typecheck/TcPolyType.lhs
deleted file mode 100644 (file)
index 7dd3973..0000000
--- a/ghc/compiler/typecheck/TcPolyType.lhs
+++ /dev/null
@@ -1,110 +0,0 @@
-%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1994
-%
-\section[TcPolyType]{Typechecking user-specified @PolyTypes@}
-
-\begin{code}
-module TcPolyType ( tcPolyType ) where
-
-#include "HsVersions.h"
-
-import TcMonad         -- typechecking monad machinery
-import AbsSyn          -- the stuff being typechecked
-
-import AbsUniType      ( mkTyVarTemplateTy, mkSysTyVarTemplate, mkSigmaTy,
-                         mkForallTy, SigmaType(..)
-                       )
-import CE              ( CE(..) )
-import Maybes          ( Maybe(..) )
-import TCE             ( TCE(..), UniqFM )
-import TVE             -- ( mkTVE, plusTVE, unitTVE, lookupTVE_NoFail, TVE(..) )
-import TcContext       ( tcContext )
-import TcMonoType      ( tcMonoType )
-import Util
-\end{code}
-
-The TVE passed into @tcPolyType@ binds type variables which are
-in scope; in practice this is always either empty (ordinary type sigs)
-or a singleton (class signatures).  @tcPolyType@ generates a type which
-is polymorphic in all the {\em other} type varaibles mentioned in the
-type.
-
-Very Important Note: when we have a type signature in an interface, say
-\begin{verbatim}
-       f :: a -> b -> a
-\end{verbatim}
-which of the following polytypes do we return?
-\begin{verbatim}
-       forall a b. a -> b -> a
---or
-       forall b a. a -> b -> a
-\end{verbatim}
-
-It makes a difference, because it affects the order in which f takes
-its type arguments.  Now this makes a difference in two ways:
-\begin{itemize}
-\item
-It's essential to get it right if an inlining for f is also exported
-by the interface.
-\item
-It's essential to get it right if the interface tells that there's a specialised
-version of f, because specialisations are known by their function-name/type-arg 
-combinations.
-\end{itemize}
-
-By convention, the foralls on a type read in from somewhere (notably interfaces)
-are 
-       {\em in alphabetical order of their type variables}
-
-When printing types we make sure that we assign print-names to the forall'd type
-variables which are also in alphabetical order.
-
-\begin{code}
-tcPolyType :: CE -> TCE -> TVE  -> RenamedPolyType -> Baby_TcM UniType
-
-tcPolyType ce tce tve (ForAllTy tvs ty)
-  = let
-       new_tv_tmpls_w_uniqs = map tc_uf_tyvar_template tvs
-       new_tv_tmpls         = map snd new_tv_tmpls_w_uniqs
-       new_tve
-         = foldr plusTVE tve
-           [ unitTVE u (mkTyVarTemplateTy tv)
-           | (u, tv) <- new_tv_tmpls_w_uniqs ]
-    in
-    tcMonoType ce tce new_tve ty       `thenB_Tc` \ new_ty ->
-    returnB_Tc (mkForallTy new_tv_tmpls new_ty)
-  where
-    tc_uf_tyvar_template (Short u _) = (u, mkSysTyVarTemplate u SLIT("a"))
-
-tcPolyType ce tce tve (OverloadedTy   ctxt ty) = tc_poly ce tce tve ctxt ty
-tcPolyType ce tce tve (UnoverloadedTy ty)      = tc_poly ce tce tve []   ty
-
-tc_poly ce tce tve ctxt ty
-  = let        -- BUILD THE NEW TVE
-       used_tyvar_names        = extractMonoTyNames (==) ty
-       poly_tyvar_names        = drop_tyvars_if_in_TVE used_tyvar_names
-
-       -- Sort them into alphabetical order; see notes above.
-       sorted_tyvar_names      = sortLt lt_by_string poly_tyvar_names
-
-       (local_tve, tyvars, _)  = mkTVE sorted_tyvar_names
-       new_tve                 = plusTVE tve local_tve
-    in
-        -- TYPE CHECK THE CONTEXT AND MONOTYPE
-    tcContext ce tce new_tve ctxt      `thenB_Tc` \ theta ->
-    tcMonoType ce tce new_tve ty       `thenB_Tc` \ tau_ty ->
-
-        -- BUILD THE POLYTYPE AND RETURN
-    returnB_Tc (mkSigmaTy tyvars theta tau_ty)
- where
-    drop_tyvars_if_in_TVE [] = []
-    drop_tyvars_if_in_TVE (n:ns)
-      = let rest = drop_tyvars_if_in_TVE ns
-       in
-       case (lookupTVE_NoFail tve n) of
-         Just _    -> rest     -- drop it
-         Nothing   -> n : rest
-
-    lt_by_string :: Name -> Name -> Bool
-    lt_by_string a b = getOccurrenceName a < getOccurrenceName b
-\end{code}