shithub: MicroHs

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Better pretty printing.

--- a/src/MicroHs/Exp.hs

+++ b/src/MicroHs/Exp.hs

@@ -12,11 +12,12 @@

   app2, cCons, cNil, cFlip,

   allVarsExp, freeVars,

   ) where

-import Prelude

+import Prelude --Xhiding((<>))

 import Data.Char

 import Data.List

 import MicroHs.Ident

 import MicroHs.Expr(Lit(..), showLit, eqLit)

+import Text.PrettyPrint.HughesPJ

 --Ximport Control.DeepSeq

 --Ximport Compat

 --Yimport Primitives(NFData(..))

@@ -52,6 +53,9 @@

   | Lit Lit

   --Xderiving (Show, Eq)

+--pattern Let :: Ident -> Exp -> Exp -> Exp

+--pattern Let i e b = App (Lam i b) e

+

 --Winstance NFData Exp where rnf (Var i) = rnf i; rnf (App f a) = rnf f `seq` rnf a; rnf (Lam i e) = rnf i `seq` rnf e; rnf (Lit l) = rnf l

 eqExp :: Exp -> Exp -> Bool

@@ -174,12 +178,12 @@

 quoteString :: String -> String

 quoteString s =

   let

-    char c =

+    achar c =

       if eqChar c '"' || eqChar c '\\' || ltChar c ' ' || ltChar '~' c then

         '\\' : showInt (ord c) ++ ['&']

       else

         [c]

-  in '"' : concatMap char s ++ ['"']

+  in '"' : concatMap achar s ++ ['"']

 encodeString :: String -> Exp

 encodeString [] = cNil

@@ -435,12 +439,16 @@

 -}

 showExp :: Exp -> String

-showExp ae =

+showExp = render . ppExp

+

+ppExp :: Exp -> Doc

+ppExp ae =

   case ae of

-    Var i -> showIdent i

-    App f a -> "(" ++ showExp f ++ " " ++ showExp a ++ ")"

-    Lam i e -> "(\\" ++ showIdent i ++ ". " ++ showExp e ++ ")"

-    Lit l -> showLit l

+--    Let i e b -> sep [ text "let" <+> ppIdent i <+> text "=" <+> ppExp e, text "in" <+> ppExp b ]

+    Var i -> ppIdent i

+    App f a -> parens $ ppExp f <+> ppExp a

+    Lam i e -> parens $ text "\\" <> ppIdent i <> text "." <+> ppExp e

+    Lit l -> text (showLit l)

 substExp :: Ident -> Exp -> Exp -> Exp

 substExp si se ae =

-- 

⑨