hopefully complete and correct typechecker in PGF

src/PGF/Expr.hs-boot

@@ -1,13 +1,17 @@
 module PGF.Expr where
 
+import PGF.CId
 import qualified Text.PrettyPrint as PP
 import qualified Text.ParserCombinators.ReadP as RP
 
 data Expr
 
-instance Eq  Expr
-instance Ord Expr
+instance Eq   Expr
+instance Ord  Expr
+instance Show Expr
 
 pFactor :: RP.ReadP Expr
 
-ppExpr :: Int -> Expr -> PP.Doc
+ppExpr :: Int -> [CId] -> Expr -> PP.Doc
+
+freshName :: CId -> [CId] -> CId