another change for R4RS; peek-char

[Chris Hanson <cph@zurich.ai.mit.edu>]

   Date: Tue, 30 May 89 17:08:52 PDT
   From: William Clinger <will@fog.cs.uoregon.edu>

   One person has objected, strongly, to making list-ref and list-tail
   essential.  Does anyone wish to counter by explaining just why it
   is essential that these procedures be essential?

The reason is the following (extracted from the Working Group on
Scheme's unapproved minutes of the Feb. 3 meeting):

    6.1  Procedures to be deleted from the standard.

    Moved, seconded, and approved: keep LIST-REF, LIST-TAIL, and
    SUBSTRING, and delete STRING->LIST, LIST->STRING, STRING-COPY,
    STRING-FILL!, VECTOR->LIST, LIST->VECTOR, and VECTOR-FILL!.  Since
    LIST-REF and LIST-TAIL are non-essential features in R4RS, we need the
    author's agreement to change them to essential.

This is required because the Working Group does not wish to
standardize on anything that is inessential in R*RS.  If R*RS decides
to keep these procedures inessential, the WG will be forced to drop
them from the standard.

I suppose this can be thought of as a strong recommendation from the
WG to R*RS that it is desirable to keep these procedures.