[Haskell-cafe] Design of extremely usable programming language libraries

[Roman Cheplyaka]

* Andrey Chudnov <achudnov at gmail.com> [2013-05-28 16:36:14-0400]
> * Does any generic traversal/transformation (uniplate-style) library
>   support GADTs?

Any syb-style library works with GADTs, by the virtue of dealing with
value representations instead of type representations.

> * What is the best choice, performance- and memory-wise, for a parser
>   combinator  library with support for arbitrary look-ahead? Parsec is
>   considered slow by some [1], but is it only in comparison with
>   attoparsec (which, unfortunately, doesn't support arbitrary
>   look-ahead)? Is there any parser library that performs better than
>   Parsec while still supporting arbitrary look-ahead.

Not sure what you mean here — attoparsec does support unlimited
lookahead, in the sense that a parser may fail arbitrarily late in the
input stream, and backtrack to any previous state.
Although attoparsec is a poor choice for programming language parsing,
primarily because of the error messages.

Roman