Re: Is add-to-list supposed to work when lexical-binding is t?

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> > (let ((x '(a))) (add-to-list 'x 'b) x) -> (b a)
>> Yup, this is asking for trouble.  Use `push' or `cl-pushnew' instead.
> Unless you're knee-deep in the internals of the language, the difference
> between `cl-pushnew' and `add-to-list' is so obscure as to be
> incomprehensible.

Agreed.  I never liked add-to-list, and now I really know why.

To give you an idea of why `add-to-list' is a problem:

   (add-to-list 'o 'b)

does the same as

   (add-to-list (intern (substring "ouch" 0 1)) 'b)

so other than by ad-hoc handling the case where the first arg is passed
via quoting, the byte-compiler would have to handle both cases, and the
second case is pretty hopeless.

   
        Stefan