Re: Proposal: die to System.Exit (and/or Prelude)

* Ivan Lazar Miljenovic [2013-12-17 00:00:16+1100]

On 16 December 2013 22:15, Roman Cheplyaka wrote:

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* Herbert Valerio Riedel [2013-12-16 10:53:21+0100]

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Why not simply use the existing `fail :: String -> IO a` method instead?

The purpose of 'fail' is to handle monadic pattern-match failures. I consider explicit use of 'fail' in user code a hack.

Or for use with parser-combinator libraries (though I suppose this could be seen as a pattern-match failure...)?

I'd consider that an abuse, too. E.g. Parsec provides a parserFail function that you can call instead. I treat 'fail' as a semi-private method of the Monad class. I may override it, but I should never call it. It only exists for the compiler. Roman