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_______________________________________________
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