Jules, Thanks for these comments. i wouldn't judge Haskell solely on the basis of whether it embraced reflection as an organizing computational principle or as a toolbox for programmers. Clearly, you can get very far without it. And, it may be that higher-order functional gives you enough of the 'programs that build programs' capability that 80% of the practical benefits of reflection are covered -- without having to take on the extra level of complexity that reflection adds to typing. i was really just seeking information.
Best wishes, --greg On 9/11/07, Jules Bean <[EMAIL PROTECTED]> wrote: > > Greg Meredith wrote: > > Haskellians, > > > > Am i wrong in my assessment that the vast majority of reflective > > machinery is missing from Haskell? Specifically, > > > > * there is no runtime representation of type available for > > programmatic representation > > * there is no runtime representation of the type-inferencing or > > checking machinery > > * there is no runtime representation of the evaluation machinery > > * there is no runtime representation of the lexical or parsing > > machinery > > > As far as they go, those are true. > > Haskell compiler are permitted to erase types and GHC does so. There is > no need to check types at runtime; that's the point of the system! There > is no evaluator, or parser, built in to the standard libraries. (The > lexer, or a version of it, is embedded in actual fact but that's not > very exciting). > > However, one should not draw too strong negative conclusions from this. > It is possible to get suprisingly far with more powerful, more typesafe > techniques without surrendering the the pure dynamism of languages that > lack compile-time guarantees. Deriving Typeable and Data is one tool > which is useful. > > It is quite possible to embed a haskell compiler, see hs-plugins. > > Jules > -- L.G. Meredith Managing Partner Biosimilarity LLC 505 N 72nd St Seattle, WA 98103 +1 206.650.3740 http://biosimilarity.blogspot.com
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