In CLOS, instance remorphing considered useless in practice?

Vladimir Sedach vas at
Wed Dec 16 20:22:24 UTC 2020

Hans Hübner <hans.huebner at> writes:
> Parallelism is something that requires proper abstractions. Some
> say that these can be just on the library level, but my experience
> tells me a different story. I find it difficult to create robust
> parallel solutions in languages like Lisp, as the language itself
> assumes a single thread of control in how it makes variable
> bindings accessible and how information is passed between
> invocations of functions by reference.

If "how information is passed between invocations of functions by
reference" is the problem, then it sounds like you really do not want
a Lisp, but Lisp Flavoured Erlang.

You have to ask: is parallelism the problem, or concurrency?

Good approaches to parallelism have already been worked out for Lisp
a long time ago: Connection Machine Lisp, *Lisp, Paralations, NESL.
What is not here now is an implementation of any of those for GPUs.

Kelly Murray worked on a multi-processor Common Lisp (Top Level
Common Lisp) in the late 1980s/early 1990s, and I think his opinion
about Common Lisp is still true today:

"This is one reason why I believed Common Lisp was good for
multiprocessing, since you can use macros to create new higher-level
parallel constructs, which is not possible with C/C++. Stuff like
parallel-do's and parallel-maps, and sequence operations can be
macros that expand into "low-level" code."

Vladimir Sedach
Software engineering services in Los Angeles

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