[slime-devel] buffer readtables
heller at common-lisp.net
Mon Sep 28 06:23:41 UTC 2009
* Sidney Markowitz [2009-09-27 22:13+0200] writes:
> Helmut Eller wrote, On 28/9/09 7:21 AM:
>> First let me say that I have little sympathy for custom readtables.
>> People who use custom syntax are fighting their tools.
> Can you say a little more about this? The only time I've used a custom
> readtable was when I was implementing a custom non-Lisp language for the
> application that was purpose-designed for the applications and its
> users, using a custom readtable and macros to translate the application
> language into s-expressions and then taking it from there in Lisp. One
> advantage was that user scripts could be compiled into fasls.
> I didn't have a problem with the result, but I would like to hear the
> arguments for doing it a better way if I ever do something similar in
> the future.
Typical problems with custom syntax:
- it's harder for the compiler to track source locations. Some
compilers, e.g CCL, use the reader to mark source expressions with
file positions. With custom readtables that's not done.
- many people forget about *read-suppress*
- the editor can't indent the code or it must be told how to do so
- the readtable is part of the compile-time environment and tools like
ASDF must be told how to deal with it
- after a month of absence even the author has forgotten how the reader
marco was supposed to work
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