Hi, I am trying out Alex. I copied the calculator specification file from Alex's official document and changed the wrapper type from "basic" to "monad". However, after I generated the ".hs" file from the lexical specification and compiled the ".hs" file, I got the message "Variable not in scope: `alexEOF'". I cannot find explanation about this 'alexEOF' function in the document. Can any body be kindly enough to tell me what this function is? Should I write it myself or not? My lexical code is listed as the below. Thanks a lot. { module Lex where } %wrapper "monad" $digit = 0-9 -- digits $alpha = [a-zA-Z] -- alphabetic characters tokens :- $white+ ; "--".* ; let { \s -> Let } in { \s -> In } $digit+ { \s -> Int (read s) } [\=\+\-\*\/\(\)] { \s -> Sym (head s) } $alpha [$alpha $digit \_ \']* { \s -> Var s } { -- Each action has type :: String -> Token -- The token type: data Token = Let | In | Sym Char | Var String | Int Int deriving (Eq,Show) } -- Xiong, Yingfei (熊英飞) Ph.D. Student Institute of Software School of Electronics Engineering and Computer Science Peking University Beijing, 100871, PRC. Web: http://xiong.yingfei.googlepages.com