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From: barmar@leander.think.com (Barry Margolin)
Newsgroups: comp.lang.lisp
Subject: Re: Linking and MACL (really efficiency of local functions)
Message-ID: <31762@news.Think.COM>
Date: 22 Nov 89 21:44:33 GMT
References: <21316@brunix.UUCP> <1989Nov20.150510.20700@hellgate.utah.edu> <SIMON.89Nov21182043@bear.UUCP> <Nov.22.12.11.49.1989.1498@atanasoff.rutgers.edu>
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In article <Nov.22.12.11.49.1989.1498@atanasoff.rutgers.edu> lou@atanasoff.rutgers.edu (Lou Steinberg) writes:
>There is another issue with LABELS and FLET: interactive programming
>environments for LISP (at least the ones I am familiar with) do not
>have good ways to handle local functions.  E.g. to trace a function,
>you must give the function name, and what gets traced is the global
>function definition.  There is no way to even specify that you want
>tracing for a local definition.  There are similar problems with
>anonymous functions, e.g. closures produced with FUNCTION.

Both Common Lisp implementations I'm familiar with -- Symbolics and Lucid
-- have names for local functions.  They are named (:INTERNAL <parent> <n>
<name>), where <parent> is the name of the function containing the local
definition, <n> is an index used to distinguish multiple local functions in
the same parent, and <name> is an optional name produced when FLET, LABELS,
or SYS:NAMED-LAMBDA are used (anonymous local functions are just named
(:INTERNAL <parent> <n>).  You can pass these names to TRACE, DISASSEMBLE,
etc.

You are right that development environments don't deal with local functions
as well as with top-level functions.  For instance, control-shift-A in
Zmacs, which is supposed to show the argument list of the function in the
form surrounding the cursor, doesn't recognize local function names (of
course, if you follow the age-old guideline of keeping your function
definitions within a screenful in size, you should only need to look up a
few lines to find this information).

Barry Margolin, Thinking Machines Corp.

barmar@think.com
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