diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/PGF/Expr.hs | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/src/PGF/Expr.hs b/src/PGF/Expr.hs index 3b8ec01bc..c586aae8c 100644 --- a/src/PGF/Expr.hs +++ b/src/PGF/Expr.hs @@ -38,7 +38,7 @@ data Tree = | Fun CId [Tree] -- ^ function application
| Lit Literal -- ^ literal
| Meta Int -- ^ meta variable
- deriving (Show, Eq, Ord)
+ deriving (Eq, Ord)
-- | An expression represents a potentially unevaluated expression
-- in the abstract syntax of the grammar. It can be evaluated with
@@ -52,7 +52,7 @@ data Expr = | EVar CId -- ^ variable or function reference
| EEq [Equation] -- ^ lambda function defined as a set of equations with pattern matching
| EPi CId Expr Expr -- ^ dependent function type
- deriving (Eq,Ord,Show)
+ deriving (Eq,Ord)
-- | The equation is used to define lambda function as a sequence
-- of equations with pattern matching. The list of 'Expr' represents
@@ -72,6 +72,12 @@ readTree s = case [x | (x,cs) <- RP.readP_to_S (pTree False) s, all isSpace cs] showTree :: Tree -> String
showTree = PP.render . ppTree 0
+instance Show Tree where
+ showsPrec i x = showString (PP.render (ppTree i x))
+
+instance Read Tree where
+ readsPrec _ = RP.readP_to_S (pTree False)
+
-- | parses 'String' as an expression
readExpr :: String -> Maybe Expr
readExpr s = case [x | (x,cs) <- RP.readP_to_S pExpr s, all isSpace cs] of
@@ -82,6 +88,12 @@ readExpr s = case [x | (x,cs) <- RP.readP_to_S pExpr s, all isSpace cs] of showExpr :: Expr -> String
showExpr = PP.render . ppExpr 0
+instance Show Expr where
+ showsPrec i x = showString (PP.render (ppExpr i x))
+
+instance Read Expr where
+ readsPrec _ = RP.readP_to_S pExpr
+
-----------------------------------------------------
-- Parsing
|