Neil,

Thanks very much for the detailed response. When we did Rosette, a reflective actor-based language, back in the late '80's and early '90's, we were very much influenced by Brian Cantwell Smith's account of reflection in 3-Lisp and similarly by Friedman and Wand's "Mystery of the Tower Revealed". Our analysis suggested the following breakdown
The Java notion of reflection is restricted entirely to the first case and then only to the data used once a normalized representation has been achieved. In fact, lexing and parsing are of considerable interest and complexity in the evaluation of programs and reflective access is extremely useful.

Likewise, access to the evaluation machinery itself is of more than theoretical interest. For example, in an ATM network management system i wrote in Rosette, i used reflective methods -- where the evaluation itself could be captured, stored and manipulated, much like a 1-shot continuation -- to make a polling interface of an external trouble-ticketing system we were required by business constraints to interface with look like an interrupt-driven interface to the Rosette-based clients.

Best wishes,

--greg

On 9/11/07, Neil Mitchell <ndmitchell@gmail.com> wrote:
Hi

> there is no runtime representation of type available for programmatic
> representation

Data.Typeable.typeOf :: Typeable a => a -> TypeRep

> there is no runtime representation of the type-inferencing or checking
> machinery

Pretty much, no. The GHC API may provide some.

> there is no runtime representation of the evaluation machinery

Yhc provides some representation with the Yhc API.

> there is no runtime representation of the lexical or parsing machinery

lex provides some of this. There are various Haskell parsers out there
in packages for us.


I wouldn't have considered these things "reflection" - certainly the
Java/C# use of the word reflection is quite different. Data.Generics
does provide many of the reflection capabilities of Java.

Thanks

Neil



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