>From: John Cowan <xxxxxx@mercury.ccil.org>
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.

--shiro