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Re: a simple counter-proposal

campbell@xxxxxxxxxxxxxxxxxxxxxxxxxxx wrote:
It occurred to me last night that a particularly simple extension to
SRFI 7 would likely appease all sides of this issue, including myself
and Felix.  (Both a proponent of the existing SRFI 55 proposal and a
proponent of Scheme48's module system on IRC have already approved of
it.)  SRFI 7's grammar would be extended in the <program> nonterminal:

  <program> -->
      (PROGRAM <program-clause>+) <command or definition>*

where <command or definition> is as defined by R5RS in section 7.1.6.
In the case that there are forms S* following the PROGRAM form that
contains clauses C*, it would be equivalent to having written a PROGRAM
form (program C* (code S*)).  For example, Felix might write a program
with SRFI 55 to display the result of (iota 5):

    (require-extension srfi-1)
    (display (iota 5))

In SRFI 7, this would be written as:

    (program (requires srfi-1)
      (code (display (iota 5))))

Felix objects to this on grounds of complexity and extra typing.  With
this new amendment proposal, the program written with SRFI 7* would be:

    (program (requires srfi-1))
    (display (iota 5))

which retains all existing functionality of SRFI 7 -- the feature
conditionalization -- and all brevity of SRFI 55's REQUIRE-EXTENSION --
it's only a single character longer, in fact --; furthermore, it is
still compatible with module systems such as that of Scheme48, because
the module data -- the configuration language -- is _still_ entirely
disjoint from Scheme, unlike the present SRFI 55's REQUIRE-EXTENSION;
the configuration language is very clearly separated from Scheme in
that the PROGRAM form is the first in the file, and every following S-
expression is Scheme.  I propose that SRFI 55 be revised to define this
amendment/extension to SRFI 7, which I expect will satisfy the demands
in brevity of Felix as well as retain the functionality of SRFIs 0 & 7,
and moreover still be as extremely portable as SRFI 7.

Just one question: what makes

(program (required srfi-1))
(display (iota 5))

more portable (in the sense of being compatible with S48's module system),

(require-extension (srfi 1))
(display (iota 55))


(provided SRFI-55 is changed in such a way that it's recommended
use is as the first expression in a file)

(While they're
at it, the SRFI 55 authors could also include a statement about trying
to make features available if they're not already available, if they
still consider the absence of such a statement in SRFI 7 an important

Well, as the document says, it's mostly at the discretion of the implementation
to specify what it means to "make an extension available", but it should perhaps
be elaborated a little.