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Re: Questions, loose ends, misprints, etc.

This page is part of the web mail archives of SRFI 83 from before July 7th, 2015. The new archives for SRFI 83 contain all messages, not just those from before July 7th, 2015.

At Thu, 01 Dec 2005 09:20:50 -0800, Per Bothner wrote:
> (library "foo-counter" "scheme://r6rs"
>    (export get-foo incr-foo)
>    (define foo 1)
>    (define-syntax get-foo
>      (syntax-rules ()
>        ((get-foo)
>         foo)))
>    (define-syntax incr-foo
>      (syntax-rules ()
>        ((incr-foo)
>         (set! foo (+ foo 1))))))
> [Not sure about the exact syntax for 'exports' - srfi-83.html
> is inaccessible right now.]
> In the example, get-foo and incr-foo are exported, but foo itself is
> not.  The compiler can prove that foo is never modified expect by
> using incr-foo.

Good point. With `syntax-rules', this is often the case, though it
requires some analysis. With a more expressive macro system (e.g.,
`syntax-case'), the analysis quickly becomes difficult.

We're planning ahead for an expressive macro system. The idea begin
`indirect-export' is as follows: the compiler should be able to produce
good results for local definitions (even when expressive macros are
defined or imported) without an especially sophisticated analysis of
macro transformers.