[r6rs-discuss] [Formal] Vector size in the read 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.

To expand on current practice, I tested the proposed
notation in several systems I have handy:

                        '#4(0 1 2 3)    '#4(0 1)

Bigloo 2.7a             error           error
Petite Chez 7.0a        #4(0 1 2 3)     #4(0 1 1 1)
Chicken 2,3             error           error
Gambit-C v4.0b20        error           error
Larceny v0.92b          error           error
MIT Scheme 7.7.90.+     error           error
MzScheme v352           #4(0 1 2 3)     #4(0 1 1 1)
Scheme 48 v1.3          error           error

The few systems that allow the proposed syntax also use
it (by default) when writing vectors, which has been a
barrier to portability.  There are two obvious ways to
fix this non-portability: require the implementations
that are using the syntax to stop using it (as was done
by the current draft), or require all implementations
to support it (as the comment proposes).

Will