From: Lassi Kortela <lassi@lassi.io>
To: guile-devel@gnu.org
Subject: Re: Add internal definitions to derived forms
Date: Fri, 18 Nov 2022 12:22:09 +0200 [thread overview]
Message-ID: <8187541f-a4e0-2f26-e8b7-df7fb82bb9f0@lassi.io> (raw)
In-Reply-To: <a27a5470-58b3-4c54-a3d5-1c27ad7d8bf9@app.fastmail.com>
> Not quite. Guile extends the lambda body (and by extension let-forms) to allow mixed definitions and expressions:
>
> (lambda ()
> (display "Heippa!")
> (define routsi #t)
> (and (read) routsi))
>
> which expands to, more or less, a letrec*. All in accordance to the paper fixing letrec(reloaded).
>
> Thus saying that the cond clause body is like a lambda body is probably the simplest way to express it.
R7RS defines the syntax of `let` et.al. as follows (section 3.5):
(let (<binding spec>*) <tail body>)
Where:
<tail body> = <definition>* <tail sequence>
<tail sequence> = <expression>* <tail expression>
So their definition of lambda:
(lambda <formals> <definition>* <expression>* <tail expression>)
could be abbreviated:
(lambda <formals> <tail body>)
I haven't read "Fixing letrec" but it looks like Guile intents to
redefine <tail body> as follows:
<tail body> = <definition-or-expression>* <tail expression>
<definition-or-expression>* = <definition> | <expression>
R6RS appears to use <tail body> in the same sense as R7RS.
next prev parent reply other threads:[~2022-11-18 10:22 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-09 15:32 Add internal definitions to derived forms Linus Björnstam
2022-11-09 15:46 ` Damien Mattei
2022-11-17 7:25 ` lloda
2022-11-18 9:04 ` Linus Björnstam
2022-11-18 9:27 ` Lassi Kortela
2022-11-18 9:50 ` Linus Björnstam
2022-11-18 10:22 ` Lassi Kortela [this message]
2022-11-18 12:53 ` Linus Björnstam
2022-11-18 13:18 ` Lassi Kortela
2023-01-19 17:54 ` lloda
2023-01-20 17:37 ` lloda
2023-01-23 22:13 ` Ludovic Courtès
2023-01-23 23:28 ` lloda
2023-01-24 7:33 ` Linus Björnstam
2023-01-24 9:02 ` Ludovic Courtès
2023-01-24 17:59 ` lloda
2023-01-25 10:33 ` Ludovic Courtès
2023-01-25 15:09 ` Ludovic Courtès
2023-01-25 15:38 ` Greg Troxel
2023-01-25 21:38 ` Linus Björnstam
2023-01-25 21:06 ` Linus Björnstam
2023-02-02 11:17 ` lloda
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