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letrec-mixed combinatorial explosion

This page is part of the web mail archives of SRFI 24 from before July 7th, 2015. The new archives for SRFI 24 contain all messages, not just those from before July 7th, 2015.

Hello everybody,

The proposal has me wondered if letrec-mixed is 
actually a part of the proposal (in the sense that a
SRFI-24 compliant Scheme has to provide it), or if
it is just a way to explain the semantics of
internal define-syntaxen.

I would recommend against making letrec-mixed obligatory.
The reason is that tomorrow somebody wants to add 
internal SRFI-9 record types, then somebody wants to add
internal define-values, and so on and so on.

Doing all this with letrex-mixed2, letrec-mixed3, etc. gets
old very fast. We get a combinatorial explosion of
possible letrex-mixed's. Already with define-syntax, define-values
and SRFI-9 we have 2^3 = 8 possible letrec's (including the
original R5RS letrec).

So IMHO it is fine to describe the effect of internal define-syntax
in terms of some helper function, but please refrain from
requiring implementations to provide letrec-mixed.


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