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Re: Why is booleanp defined this way?


From: Stefan Monnier
Subject: Re: Why is booleanp defined this way?
Date: Sat, 18 Apr 2015 01:03:23 -0400
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux)

>> Elisp does not have a proper boolean type; unlike say symbols with
>> symbolp, strings with stringp, numberp -- some union of numeric types etc.
>> However programmers need boolean in their ontology even if (and even more if)
>> the language does not support it.
> Well, if you go this way, elisp doesn't have proper types at all!!!

I think he was alluding to the difference between the types that
`typeof' might recognize and those that are more like unions of other types.

> deftype, typep, subtypep are all defined in cl.el and as such, "frowned
> upon" by the PTB.

cl-deftype, cl-typep, ... are alive and well and not frowned upon.


        Stefan


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