[Haskell-cafe] Using regexps to filter data

michael rice nowgate at yahoo.com
Sun Mar 14 22:43:41 EDT 2010

Not sure I'm even in the right neighborhood with this. Need to screen for integer data. 
Am I going about this correctly?



[michael at localhost ~]$ ghci
GHCi, version 6.10.4: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
Prelude> :m + Text.Regex.Base.RegexLike
Prelude Text.Regex.Base.RegexLike> let r = makeRegex "[+-]?[0-9]+"

    No instance for (RegexMaker regex compOpt execOpt [Char])
      arising from a use of `makeRegex' at <interactive>:1:8-30
    Possible fix:
      add an instance declaration for
      (RegexMaker regex compOpt execOpt [Char])
    In the expression: makeRegex "[+-]?[0-9]+"
    In the definition of `r': r = makeRegex "[+-]?[0-9]+"
Prelude Text.Regex.Base.RegexLike> 

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