From: Per Bothner <per@bothner.com>
To: kawa@sourceware.org
Subject: Re: Extending functional call syntax for Sequences to include Maps
Date: Wed, 15 Jul 2020 22:24:00 -0700 [thread overview]
Message-ID: <31607c53-66ce-895e-4fc9-73471c8e51bc@bothner.com> (raw)
In-Reply-To: <CA+ghDQ8z=DeykLszLY3LeoSmXvKZ+VpWDU7UKWAOf4YCPNEATQ@mail.gmail.com>
On 7/15/20 11:44 AM, Jamison Hope wrote:
> I suspect you're remembering this conversation we had five (!) years ago:
> https://sourceware.org/pipermail/kawa/2015q1/006284.html
Only five? I see ChangeLog entries with your name going back to 2009 ....
> You were leaning toward throwing an exception on no-default, and I was
> leaning toward returning #!null for simplicity/consistency with Java,
> and also because #!null is treated as false, which is like what
> assq/assv/assoc and memq/memv/member return for an absent key.
I still feel more comfortable with throwing an exception if KEY is invalid
in the (HMAP KEY) case. I think passing a default argument
doesn't really need a keyword - (HMAP KEY DEFAULT) looks good to me.
I don't expect I'll be implementing this feature anytime soon - perhaps
an interesting project for someone? It's not completely trivial
because of the compile-time handling of "ApplyToArgs".
You also mentioned hash literals. I'm not as keen on a syntax
that only works for literal maps - I'd like an elegant syntax that
works for keys and values that are expressions evaluated at run-time.
Conceptually similar to the sequence syntax:
[E0 E1 ... ELAST]
One approach is to use quasi-quotation, though I think that's a bit ugly.
--
--Per Bothner
per@bothner.com http://per.bothner.com/
prev parent reply other threads:[~2020-07-16 5:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-03 21:24 Duncan Mak
2020-07-03 22:05 ` Per Bothner
2020-07-04 4:07 ` Duncan Mak
2020-07-15 18:44 ` Jamison Hope
2020-07-16 5:24 ` Per Bothner [this message]
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