Re: Declaring Lisp function types

[Alan Mackenzie <acm@muc.de>]

Hello, Andrea.

On Fri, Feb 23, 2024 at 11:02:52 -0500, Andrea Corallo wrote:
> Hi all,

> I'm looking into moving out the function type declarations in
> 'comp-known-type-specifiers' in order to move them to where the function
> are actually defined.  This to easy maintenance (ATM they get out of
> sync) and to allow the user for (indeed optionally) declaring function
> types.

> In principle I believe we are interested in expressing the the argument
> types and (maybe optionally) the return type.

What's missing is the why.  Do we actually want to put function type
declarations in Lisp source at all?  They will clutter up the code more
than it is cluttered up at the moment.

A ground principle of Lisp is that type checking is done at run time,
not compile time.  Your proposal seems to be changing that, although I
don't know what the intention for using the type decorations is.

I worry that these declarations will become frequent, even pervasive,
and then effectively compulsory.  Then we won't have Lisp any more,
we'll have something more like C.

I think somebody said somewhere that the declarations will be
"voluntary", but things that start off voluntary have a nasty habit of
first becoming pervasive, then all but universal, and then compulsory.

As I said, I don't know what these declarations are for, but I think
serious thought should be given to not implementing them.

[ .... ]

> Thanks!

>   Andrea

-- 
Alan Mackenzie (Nuremberg, Germany).