Haskell parsec parsing a string of items

Posted by Chris on Stack Overflow See other posts from Stack Overflow or by Chris
Published on 2010-03-15T16:23:30Z Indexed on 2010/03/15 18:29 UTC
Read the original article Hit count: 366

Filed under:

haskell

|

parsec

I have a list that I need to parse where the all but the last element needs to be parsed by one parser, and the last element needs to be parsed by another parser.

a = "p1 p1b ... p2"
or
a = "p2"

Originally I tried

parser = do parse1 <- many parser1
            parse2 <- parser2
            return AParse parse1 parse2

The problem is that parse1 can consume a parse2 input. So parse1 always consumes the entire list, and leave parse2 with nothing.

Is there a way to say to apply parse1 to everything besides the last element in a string, and then apply parse2?

© Stack Overflow or respective owner

Related posts about haskell

Learning Haskell: How to remove an item from a List in Haskell

as seen on Stack Overflow - Search for 'Stack Overflow'
Trying to learn Haskell. I am trying to write a simple function to remove a number from a list without using built-in function (delete...I think). For the sake of simplicity, let's assume that the input parameter is an Integer and the list is an Integer list. Here is the code I have, Please tell me… >>> More
Using Data.Heap in Haskell, or reading Haskell docs for a beginner

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm trying to use Haskells Data.Heap module, but I'm incapable of even using it with integers. The only heap I've been capable of using is "empty", which does not take any arguments. Later on I'll figure out how to instance for my needs, but for now I'd be glad if I was even able to test it with… >>> More
What kind of things are easy in Haskell and hard in Scala, and vice versa?

as seen on Programmers - Search for 'Programmers'
There has been some intermingling of Scala and Haskell communities, and I have noticed now and then people commenting on stuff that's supposed to be easy in Haskell and hard and Scala. Less often (maybe because I read Scala questions, not Haskell ones), I see someone mentioning that something in Scala… >>> More
Haskell's cabal dependency problem with happy

as seen on Programmers - Search for 'Programmers'
I have problems installing ghc-mod on my linux machine. cabal worries about "happy" not being available in versione = 1.17: $ cabal install ghc-mod Resolving dependencies... [1 of 1] Compiling Main ( /tmp/haskell-src-exts-1.14.0-1357/haskell-src-exts-1.14.0/Setup.hs, /tmp/haskell-src-exts-1… >>> More
Understanding Haskell's fibonacci

as seen on Stack Overflow - Search for 'Stack Overflow'
fibs :: [Int] fibs = 0 : 1 : [ a + b | (a, b) <- zip fibs (tail fibs)] This generates the Fibonacci sequence. I understand the behaviour of the guards, of :, zip and tail, but I don't understand <-. What is it doing here? >>> More

Related posts about parsec

parsec-3.1.0 with custom token datatype

as seen on Stack Overflow - Search for 'Stack Overflow'
parsec-3.1.0 ( http://hackage.haskell.org/package/parsec-3.1.0 ) works with any token type. However there are combinators like Text.Parsec.Char.satisfy that are only defined for Char datatype. There doesn't seem to be any more general counterpart available. Should I define my own versions or did… >>> More
Parsec: backtracking not working

as seen on Stack Overflow - Search for 'Stack Overflow'
I am trying to parse F# type syntax. I started writing an [F]Parsec grammar and ran into problems, so I simplified the grammar down to this: type ::= identifier | type -> type identifier ::= [A-Za-z0-9.`]+ After running into problems with FParsec, I switched to Parsec, since I have a full chapter… >>> More
many1 no longer works with Parsec 3.x

as seen on Stack Overflow - Search for 'Stack Overflow'
After updating to Parsec 3.1 from 2.x, code using many1, such as word = many1 letter fails with No instance for (Stream s m Char) arising from a use of `letter' I found a mailing list post claiming that adding {-#LANGUAGE NoMonomorphismRestriction #-} to the top of the source file would solve the… >>> More
Haskell parsec parsing a string of items

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a list that I need to parse where the all but the last element needs to be parsed by one parser, and the last element needs to be parsed by another parser. a = "p1 p1b ... p2" or a = "p2" Originally I tried parser = do parse1 <- many parser1 parse2 <- parser2 … >>> More
Using Haskell's Parsec to parse binary files?

as seen on Stack Overflow - Search for 'Stack Overflow'
Parsec is designed to parse textual information, but it occurs to me that Parsec could also be suitable to do binary file format parsing for complex formats that involve conditional segments, out-of-order segments, etc. Is there an ability to do this or a similar, alternative package that does this… >>> More