Question

I am trying to write a parser in Haskell. In this I need a function that parses a string of length at least 1. I have the type declared below:

type Pname = String

but my function that I have doesn't work. The code I have is below, where sc is my space consumer for whitespace and comments (I have been following the tutorial at https://mrkkrp.github.io/megaparsec/tutorials/parsing-simple-imperative-language.html for help with this parser):

pname :: Parser Pname
pname = (some ['a' .. 'z']) <* sc

but it gives me the error:

    Couldn't match type ‘[]’
                   with ‘ParsecT Dec String Data.Functor.Identity.Identity’
    Expected type: ParsecT
                     Dec String Data.Functor.Identity.Identity Char
      Actual type: [Char]
    In the first argument of ‘some’, namely ‘['a' .. 'z']’
    In the first argument of ‘(<*)’, namely ‘(some ['a' .. 'z'])’
    In the expression: (some ['a' .. 'z']) <* sc

Any ideas on why this doesn't work?

Answer 1

Probably you meant to use oneOf (or a similar function from your parser library) as in

pname = some (oneOf ['a' .. 'z']) <* sc

to turn the list of characters into a parser that accepts one of those characters.

Parse a string of length at least one character

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