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From: Per Bothner <>
Subject: Re: Extending functional call syntax for Sequences to include Maps
Date: Wed, 15 Jul 2020 22:24:00 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 7/15/20 11:44 AM, Jamison Hope wrote:
> I suspect you're remembering this conversation we had five (!) years ago:

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

      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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