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Re: function signature type checking



In article <200111290103.UAA26709@life.ai.mit.edu>, Kim Barrett 
<kab@camellia.org> wrote:

> At 7:00 PM -0500 11/28/01, Bruce Hoult wrote:
> >It may be simply that it was difficult to see precisely what the
> >difficulties might *be* until there were actual implementations of the
> >language.  Real compilers have to deal with function signatures, and
> >they do, but the design of how to do it while coping with all possible
> >"hair" may have been best found operationally rather than specified
> >a-priori.
> 
> - The compiler writers may choose to punt on certain corner cases and 
> simply
> say it isn't worth the trouble in that case, do something conservatively
> correct.  I think all of the Dylan compilers I've looked at do this in
> some cases, just punting to the runtime system to correctly handle things
> once they've been concretized.

Right, and I don't see punting in some cases as being a horrid thing.  
remember that this is a Lisp, not ML, and we don't *insist* on getting 
everything totally nailed down and proved correct at compile time in 
every case.


> - The language specification for function signatures needs to be
> written in a way that one doesn't have to be a compiler expert to
> understand it.

As opposed, say, to the DRM explanation of argument list compatability, 
or "subtype"? :-)

-- Bruce



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