[erlang-questions] Parser combinators

Torbjorn Tornkvist <>
Thu Oct 18 09:43:39 CEST 2007


Have a look here:

http://www.engr.uconn.edu/~jeffm/Source/Erlang/

--Tobbe



Joel Reymont wrote:
> Folks,
> 
> Any suggestions on how parser combinators can be elegantly and  
> cleanly implemented in Erlang?
> 
> State needs to be threaded from combinator to combinator and I don't  
> see an option apart from either keeping the state in the process  
> dictionary or keeping it in a process launched at the beginning of  
> the parsing run.
> 
> How could the following bits of Haskell without having to deal with  
> state returned from each of reschoice, symbol, commaSep, etc.?
> 
> 	Thanks, Joel
> 
> ---
> 
> varDeclarations = do
>    reschoice [ "Variable", "Variables", "Vars", "Var" ]
>    symbol ":"
>    decs <- commaSep varDeclaration
>    return $ VarDecs decs
> 
> whileStatement = do
>    reserved "While"
>    e <- expr
>    reserved "Begin"
>    xs <- statements
>    reserved "End"
>    return $ While e (Compound xs)
> 
> ident = do
>    c <- identStart
>    cs <- many (identLetter)
>    return (c:cs)
> 
> sign = (char '-' >> return (0-1))
>         <|> (char '+' >> return 1)
>         <|> return 1
> 
> 
> --
> http://wagerlabs.com
> 
> 
> 
> 
> 




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