old/expr/exist/exist.dcl

   1 definition module exist
   2
   3 from Data.Either import :: Either
   4
   5 :: Expr
   6         = Lit Int
   7         | Var String
   8         | (+.) infixl 6 Expr Expr
   9         | E.e: Ext e & eval e & print e
  10
  11 class eval m :: m -> ([(String, Int)] -> Either String Int)
  12 class print m :: m -> String
  13
  14 instance eval Expr
  15 instance print Expr