[r6rs-discuss] [Formal] Trivial Enhancement of macros in v5.91: capture-syntax

[William D Clinger]

I am posting this as an individual member of the Scheme
community.  I am not speaking for the R6RS editors, and
this message should not be confused with the editors'
eventual formal response.

Andre van Tonder quoting me:

> > ... the reference implementation
> > of arithmetic will be invoked twice, making some of their
> > fundamental types incompatible.
>
> Would the fundamental types not be more naturally non-generative, or am I
> missing some aspect of generativity?

Yes, they would be non-generative, but with the draft
R6RS that is expressed by using a symbol.  With the
separated binding, invoke-separately-for-each-phase
semantics, an L1-symbol is not an L0-symbol.  Thus
even the non-generative types are different in L0
and L1.

With the shared binding, invoke-once semantics,
non-generative record types work as programmers
expect, but the draft R6RS doesn't guarantee that
semantics.

Will