HLL is not against LLL

Francois-Rene Rideau fare@Sit-Hyps
Sun, 2 Jul 1995 22:19:01 +0200 (MET DST)

Patrick wrote:
> I don't think we need to specify a standard LLL for TUNES.  What we
> want is to be able to take a HLL program and execute it.  How that is
> done is an implementation detail.
   Well, this is an interesting point of view; and I already told
how I think that eventually, such point of view would prevail, and that
many completely different implementations could exist for our HL objects.
But we have to write a first implementation before there are many of
them; and what this implementation is is important to us; so even though
the aim of the LLL is not to be universal, still, it is not out of the
scope of the project.

> The first HLL (Tunes)
> implementations may well be interpreters, in which case a LLL would of
> no use as a target language. Also, I doubt a LLL would be useful as as
> a host language for Tunes implementations since it's much easier to
> implement such a complex programming system in a HLL.
> A LLL may be
> developed for portability reasons in a HLL compiler but it is not
> necessary.
   I am still convinced that a LLL is a very good speed-up for the
development of a computing system. Bytecodes and LISP interpreters are
what I call LLLs. But they are unextensible, unadaptable LLLs. I prefer
using some FORTH-like LLL, so it can adapt to the hardware (easy to
add words written in assembly) and extend naturally into the HLL, thus
yielding much better integration.
   I'm almost sure that it is a good choice; but if you have any
arguments against that, please tell them: I'm wide open to discussion.

> The HLL implementation has to be written in itself (or a subset of
> itself) since reflectivity is a requirement (one might want to observe
> or modify the implementation dynamically).
   And the LLL is this subset of the HLL we write it into !

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