Parsec: direct style monadic parser combinators for the real world

Despite the long list of publications on parser combinators, there does \nnot yet exist a monadic parser combinator library that is applicable in real \nworld situations. In particular naive implementations of parser combinators \nare likely to suffer from space leaks and are often unable to report \nprecise error messages in case of parse errors. The Parsec parser combinator \nlibrary described in this paper, utilizes a novel implementation \ntechnique for space and time e±cient parser combinators that in case of \na parse error, report both the position of the error as well as all grammar \nproductions that would have been legal at that point in the input.