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Re: Backquote simplification
From: |
Neil Jerram |
Subject: |
Re: Backquote simplification |
Date: |
Sat, 11 Dec 2010 00:25:19 +0000 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) |
Hans Aberg <address@hidden> writes:
> The reply I got was helpful, but I decided to settle for a macro
> implementation:
>
> (use-syntax (ice-9 syncase))
>
> (define-syntax tuple
> (syntax-rules ()
> ((tuple xs ...)
> `(tuple ,xs ...))
> ((tuple x1 x2 . y)
> (append `(tuple ,x1 ,x2) y))
> ((tuple x1 . y)
> (append `(tuple ,x1) y))
> ))
OK, I roughly see that this solves your problem of wanting to unquote an
arbitrary number of list elements. (Although I don't understand why you
need to do that.)
> It behaves as I want in my context, a functional language on top of
> Guile.
Scheme is already a functional language, isn't it?
> I decided to implement the construct (lambda (x_1 ... x_k . y)
> f)
What syntax is that expression in? In Scheme syntax, it's a lambda that
returns a value that is apparently unrelated to any of the arguments,
and so could equally well be written as (lambda ignored-args f).
> using an improper list (x_1 ... x_k . y); when it is a proper list,
> one just gets the fixed number of arguments construct.
>
> Then the object (x_1 ... x_k . y) also become available, so it is
> possible to form
> (define f (lambda (x_1 ... x_k . y) (x_1 ... x_k . y)))
How is this different from
(define f (lambda args args))
?
> Then one would expect f(a_1, ..., a_n), for n >= k, to be (a_1, ...,
> a_n) - this a form of the identity.
>
> So to get this effect, I need a function g that can call improper
> lists (g x_1, ..., x_k . y), where y is a list.
As Dan pointed out, that is not an improper list. It's a proper list.
In the hope that these questions might be useful to at least one of us...
Neil
- Backquote simplification, Hans Aberg, 2010/12/09
- Message not available
- Re: Backquote simplification, Hans Aberg, 2010/12/09
- Re: Backquote simplification, Neil Jerram, 2010/12/10
- Re: Backquote simplification, Hans Aberg, 2010/12/10
- Re: Backquote simplification,
Neil Jerram <=
- Re: Backquote simplification, Hans Aberg, 2010/12/11
- Re: Backquote simplification, Neil Jerram, 2010/12/11
- Re: Backquote simplification, Hans Aberg, 2010/12/11