Right-to-left (was: Re: entry a

[mcdonald at uxe.cso.uiuc.edu]

In article <818 at skye.ed.ac.uk> richard at aiai.UUCP (Richard Tobin) writes:
>.... there are lisp systems without an interpreter at all -
>when you type in an expression, they compile it and execute the code
>immediately.

and ray at philmtl.philips.ca replies:
>This just shows that a very hazy line separates "compilers" and "interpreters".

>There are many of us who would still call such an incremental compiler an
>interpreter.

There is an obvious distinction between an incremental compiler
and an interpreter: an incremental compiler generates actual machine
code of the CPU at hand (NOT pseudocode) and then executes it.

As an example of the importance of the distinction, it is very easy
to write an interpreter for just about any language in C. (Well,
easy in concept.) 

BUT, the C standard does not guarantee that it is even POSSIBLE to
write an incremental compiler in C. Not that it prevents it, just that
it does not guarantee that the code you generate can be executed.
It appears that there are a very few machines (&OS's) where incremental
compilers are indeed actually impossible.

Doug McDonald