How do I get Parsec to let me call `read` :: Int?

Question

I\'ve got the following, which type-checks:

p_int = liftA read (many (char \' \') *> many1 digit <* many (char \' \'))

Now, as the fu

Answer 1

p_int is a parser that produces an Int, so the type would be Parser Int or similar¹.

p_int = liftA read (many (char ' ') *> many1 digit <* many (char ' ')) :: Parser Int

Alternatively, you can type the read function, (read :: String -> Int) to tell the compiler which type the expression has.

p_int = liftA (read :: String -> Int) (many (char ' ') *> many1 digit <* many (char ' ')) :: Int

As for the cleaner ways, consider replacing many (char ' ') with spaces.

¹ ParsecT x y z Int, for example.