I have little constructive to say on the topic, except that I typically use hugs in preference to "monstrous" ghc/ghci. It's lightweight and its language is properly documented (in the Haskell 98 report), neither of which can be said of ghc. Its rudimentary instrumentation (:set +s) is more useful than ghc's equivalent, though admittedly ghc has many debugging features I haven't explored. That said, it should be noted that I do not use Haskell (nor, nowadays, any other language) for writing production code. Apropos of language, a couple of years ago I noted that ghc implements 2^99 languages, not one. (There were 99 non-antonymous language pragmas; there may be more now.) Who can know what terrors lurk there. My first attempt to investigate the field (turn on all 99) caused a compiler panic, since fixed. Early on, I encountered a hugs bug: garbage collection in the middle of a bignum operation caused havoc. Having never looked at the hugs source before, I was able quite quickly pinpoint the offending code; the maintainers corrected it almost overnight. That heart-warming experience hasn't worn off, even though the maintainers have moved on. Doug