Re: [bug #30070] multiple returns from map

[Stefan Israelsson Tampe]

Yes a tail pointer was a mind slip . But I did 
changed the final reverse! to the functional reverse in the srfi-1 version of map 
and doing that should be enough. You pay at most 2x time wise due to the need to
allocate twice as many conses, But there is no need to introduce new stack features
as far as I can see.

/Stefan

On Fri, Aug 12, 2011 at 11:03 PM, Andy Wingo <address@hidden> wrote:

Follow-up Comment #2, bug #30070 (project guile):

Stefan, the tail pointer does preserve performance, but it does not preserve
the R6RS invariant about multiple returns.

Szavai is right.  Perhaps we should provide some other definition of `map'
within R6RS to satisfy this requirement.  However, a proper solution looks
more like recursion than iteration, and to do that with arbitrary-sized lists
will require Guile to implement extendable stacks, which is a significant
hack.

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