f# - Translate Haskell parsec to FParsec -

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how translate haskell code:

import text.parsercombinators.parsec((<|>), unexpected, lookahead, noneof, char) import control.monad(when)  data bracketelement = bechar char | bechars string | becoll string | beequiv string | beclass string  p_set_elem_char =    c <- noneof "]"   when (c == '-') $     atend <- (lookahead (char ']') >> return true) <|> (return false)     when (not atend) (unexpected "a dash in wrong place in bracket")   return (bechar c)

to fparsec ? preferable way without monadic syntax provide performance.

thanks in advance, alexander.

sorry little misleading. corrected problem make haskell code compilable:

import text.parsercombinators.parsec((<|>), (<?>), unexpected, lookahead, noneof, char) import control.monad(when) import data.functor.identity import qualified text.parsec.prim pr  -- | bracketelement internal module data bracketelement = bechar char | bechars string | becoll string | beequiv string | beclass string                     deriving show  p_set_elem_char :: pr.parsect [char] u identity bracketelement   p_set_elem_char =    c <- noneof "]"   when (c == '-') $     atend <- (lookahead (char ']') >> return true) <|> (return false)     when (not atend) (unexpected "a dash in wrong place in bracket")   return (bechar c)

now possible reproduce *p_set_elem_char* computation.

i sincerely thank of helped me.

i made own approximation, unfortunately not functional be:

type bracketelement = bechar of char                      | bechars of string                      | becoll of string                      | beequiv of string                      | beclass of string  let p_set_elem_char : parser<bracketelement, _> =      fun stream ->         let statetag = stream.statetag         let reply = (noneof "]") stream         let chr = reply.result         let mutable reply2 = reply(bechar chr)         if reply.status = error && statetag = stream.statetag             reply2.status <- error             reply2.error <-  reply.error         else if chr = '-' && stream.peek() <> ']'             reply2.status <- error             reply2.error <- messageerror ("a dash in wrong place in bracket")         reply2

using bracketelement type in toyvo's answer, like

let pbechar : parser<_, unit> =    let c =      pchar '-' .>> followedbyl (pchar ']') "a dash in wrong place in bracket"     <|> noneof "-]"   c |>> bechar

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