[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

whether #!identifiers are datums

This page is part of the web mail archives of SRFI 103 from before July 7th, 2015. The new archives for SRFI 103 contain all messages, not just those from before July 7th, 2015.

This isn't very relevant to SRFI 103, but it comes up
from time to time.

Derick Eddington wrote:
> I thought #!identifier lexical tokens are considered comments at a level
> below "syntactic datums".  I, of course, meant the first thing the
> standard read procedure would return.  I thought calling that a "datum"
> was the normal terminology.

#!r6rs is the only lexical token of that form that is
guaranteed to be a comment.  Tokens such as #!undefined
and #!eof are unlikely to be comments in implementations
that support such things.

In R6RS systems, whether implementation-dependent directives
like #!fold-case and #!no-fold-case are comments is also
implementation-dependent.  In ERR5RS, those directives are
datums, not comments, and apply only to the port from which
they are read; if someone wants to change the case-folding
mode for a port without adding a datum, one of those tokens
can be preceded by a #; token.  See the end of