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Re: New draft

This page is part of the web mail archives of SRFI 89 from before July 7th, 2015. The new archives for SRFI 89 contain all messages, not just those from before July 7th, 2015.

Marc Feeley <feeley@iro.umontreal.ca> writes:

> The new syntax does away with the `#!optional', `#!key' and `#!rest'
> markers.  Instead, a syntax that is inspired from EBNF is used to
> denote optional parts (square brackets in the parameter list around
> the optional parameters).

Considering that R6RS will standardize brackets as being
equivalent to parentheses[1], this SRFI will also allow

  (define (myproc required (optional #f) (key: key #t))

I assume this is intended, and I want to state that I like this
syntax, and I definitively prefer it very much over the old.

It /might/ be preferable to some people if this SRFI would specify
LAMBDA-KW and DEFINE-KW special forms (the names up for debate of
course) instead of shadowing R5RS’ forms. A useful module system
can be used to explicitly shadow the R5RS forms if someone
requires the extended capabilities in LAMBDA and DEFINE itself.

This SRFI allows the following function definition:

  (define (foo (bar: bar 2) (baz 3))

But for this procedure, it would disallow the analogical

  (foo bar: 5 'baz-value)

In this example, BAZ is bound to the keyword BAR:, and the
application then is invalid due to too many arguments. To make
this dependence on order explicit, I think it would be useful to
only allow optional arguments to be specified before keyword

        -- Jorgen

[1] The March 2005 R6RS Status Report

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