Improve pretty printing for indexed type decls

Wed Aug 16 17:01:59 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
  * Improve pretty printing for indexed type decls

diff --git a/compiler/hsSyn/HsDecls.lhs b/compiler/hsSyn/HsDecls.lhs
index 2515c1a..2128ad3 100644 (file)
--- a/compiler/hsSyn/HsDecls.lhs
+++ b/compiler/hsSyn/HsDecls.lhs
@@ -517,19 +517,23 @@ instance OutputableBndr name
        dcolon <+> pprKind kind
         where
          typeMaybeIso = if iso 
-                        then ptext SLIT("type iso") 
-                        else ptext SLIT("type")
+                        then ptext SLIT("type family iso") 
+                        else ptext SLIT("type family")
 
     ppr (TySynonym {tcdLName = ltycon, tcdTyVars = tyvars, tcdTyPats = typats,
                    tcdSynRhs = mono_ty})
-      = hang (ptext SLIT("type") <+> pp_decl_head [] ltycon tyvars typats <+> 
+      = hang (ptext SLIT("type") <+> 
+             (if isJust typats then ptext SLIT("instance") else empty) <+>
+             pp_decl_head [] ltycon tyvars typats <+> 
              equals)
             4 (ppr mono_ty)
 
     ppr (TyData {tcdND = new_or_data, tcdCtxt = context, tcdLName = ltycon,
                 tcdTyVars = tyvars, tcdTyPats = typats, tcdKindSig = mb_sig, 
                 tcdCons = condecls, tcdDerivs = derivings})
-      = pp_tydecl (ppr new_or_data <+> 
+      = pp_tydecl (null condecls && isJust mb_sig) 
+                  (ppr new_or_data <+> 
+                  (if isJust typats then ptext SLIT("instance") else empty) <+>
                   pp_decl_head (unLoc context) ltycon tyvars typats <+> 
                   ppr_sig mb_sig)
                  (pp_condecls condecls)
@@ -573,12 +577,14 @@ pp_condecls cs@(L _ ConDecl{ con_res = ResTyGADT _ } : _) -- In GADT syntax
 pp_condecls cs                           -- In H98 syntax
   = equals <+> sep (punctuate (ptext SLIT(" |")) (map ppr cs))
 
-pp_tydecl pp_head pp_decl_rhs derivings
+pp_tydecl True pp_head pp_decl_rhs derivings
+  = pp_head
+pp_tydecl False pp_head pp_decl_rhs derivings
   = hang pp_head 4 (sep [
-       pp_decl_rhs,
-       case derivings of
-         Nothing          -> empty
-         Just ds          -> hsep [ptext SLIT("deriving"), parens (interpp'SP ds)]
+      pp_decl_rhs,
+      case derivings of
+        Nothing -> empty
+       Just ds -> hsep [ptext SLIT("deriving"), parens (interpp'SP ds)]
     ])
 
 instance Outputable NewOrData where