Subject: Re: bug#59786: Allowing arbitrary expressions in cl-labels

From: Michael Heerdegen <[email-masked]>
Date: Fri, 13 Jan 2023 14:47:52 +0100

Stefan Monnier <[email-masked]> writes:

> The patch below uses this "new new" syntax (and adjusts `cl-flet` to
> also support this new new syntax).  It still lacks a NEWS entry (as
> well as updating the CL manual), but before I do that, I'd like to hear
> what other people think,

I like the idea to implement this kind of feature for `cl-labels'.  It's
a good change IMO.

I don't like the syntax I think (ugly).  The rest of this answer is
discussing this detail:

I don't recall all details about the ambiguity of the empty body case,
so forgive me if I'm missing something.

A binding like (my-fun (var1 var2)) with an empty body would give you
compiler warnings anyway.  Would this be an alternative to your "="
style syntax:

To specify a local function with an empty body one would have to use
local variable names starting with "_":

   (my-fun (_var1 _var2))

If not all variables start with an underscore or not all list members
are symbols, the binding is interpreted as specifying an expression
evaluating to the function to bind.  This assumes that "_var" never
specifies a named function.

Michael.