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Re: New release of SRFI 114 with implementation

This page is part of the web mail archives of SRFI 114 from before July 7th, 2015. The new archives for SRFI 114 contain all messages, not just those from before July 7th, 2015.

From: John Cowan <cowan@xxxxxxxxxxxxxxxx>
Subject: Re: New release of SRFI 114 with implementation
Date: Thu, 5 Dec 2013 13:35:00 -0500

>> I agree with those disadvantages, and I'm not saying the standard
>> should use closures.  My point is to allow implementations to use
>> closures if it wants to.
> This argument seems to be perfectly general.  As we know, closures can
> emulate any data structure, so what is the argument for making, say,
> pairs and procedures disjoint?  Well, it's more convenient to be able
> to do type dispatching without worrying about whether pairs might be
> procedures.  I think the same argument applies here.
>> Or to allow a 'map' with suitable entries i.e. in Clojure notation,
>> something like {:type? type-pred, :equal? equal-proc, :hash hash-proc}
> Now the situation becomes more complicated yet: comparators might be
> hash tables or procedures or even both (since hash tables might be
> procedures).  I fear this will upset Scheme's existing balance between
> rigid (though dynamic) typing and duck typing.

Ok.  I'm not really firm about this issue; after all, we already
have the record types in place so it's not a big deal to ask
implementations to come up a disjoint type.  I withdraw my claim.