Re: PROPOSAL: Export "readEither" from Text.Read

Am 12.12.2011 16:24, schrieb Ben Millwood:

On Thu, Dec 8, 2011 at 10:39 PM, Iavor Diatchki wrote:

...

Hello,

when writing simple String parsers, I find implementing this function over and over:

readEither :: Read a => String -> Either String a

The only thing that bothers me about this is the fact that the error is a String; I don't think that's a very good type for errors, because only humans can really effectively interpret it. I don't know whether it's worth introducing a new sum type just for the different kinds of read error.

http://www.haskell.org/ghc/docs/latest/html/libraries/base-4.4.1.0/src/Text-... The current error messages are a bit stupid, anyway. An ambiguous parse could be avoided by (arbitrarily) returning the first match. Instead of "no parse" I would expect a proper char position of my error, but that's difficult to extract from the Read class.

Regardless, readMaybe is definitely a good idea, so +1 for that.

Indeed, readMaybe is a good idea and quite enough. C.