Re: [Scheme-reports] <body> of let-syntax

To: Jim Rees <jimreesma@x>

Subject: Re: [Scheme-reports] <body> of let-syntax

From: Alex Shinn <alexshinn@x>

Date: Mon, 20 Jan 2014 13:22:49 +0900

Cc: scheme-reports <scheme-reports@x>

In-reply-to: <CAHwMy1_oEi=fdcDhvjzdV4VRZs1XS0u3p2sGcH8VonS=eYNyrg@mail.gmail.com>

References: <52DC3A31.5070102@ymail.com> <CAHwMy1_oEi=fdcDhvjzdV4VRZs1XS0u3p2sGcH8VonS=eYNyrg@mail.gmail.com>

On Mon, Jan 20, 2014 at 1:08 PM, Jim Rees <jimreesma@x> wrote:

...for that matter shouldn't it also be "zero or more expressions" ?

If you wanted to make that extension, but this had not even been

proposed. This is consistent with requiring, e.g. lambda bodies be

non-empty.

Note some implementations have a let-syntax which "splices"

into the outer context, in which case having only definitions

but no expressions could be useful. But R7RS follows R5RS

with a non-splicing let-syntax.

..and while this may already have been mentioned in the past, it may not be possible to decide what the elements of <body> are (definitions or expressions) until after expanding them using the syntax definitions provided.

Yes, an implementation would need to expand before checking

for errors.

Alex