Re: [Haskell-cafe] Compilers: Why do we need a core language?

23 Nov 2012


      On 22/11/2012 11:52 AM, Brandon Allbery wrote:
...
On Thu, Nov 22, 2012 at 7:56 AM, Jacques Carette mailto:carette@mcmaster.ca> wrote:
On 20/11/2012 6:08 PM, Richard O'Keefe wrote:
On 21/11/2012, at 4:49 AM, mailto:citb@lavabit.com> wrote:
Well, I don't know. Would it save some time? Why bother
            with a core language?
For a high level language (and for this purpose, even Fortran
        66 counts as
        "high level") you really don't _want_ a direct translation
        from source code
        to object code.  You want to eliminate unused code and you
        want to do all
        sorts of analyses and improvements.  It is *much* easier to do
        all that to
        a small core language than to the full source language.
Actually, here I disagree.  It might be much 'easier' for the
    programmers to do it for a small core language, but it may turn
    out to be much, much less effective.  I 'discovered' this when
    (co-)writing a partial evaluator for Maple:
You're still using a core language, though; just with a slightly 
different focus than Haskell's.  I already mentioned gcc's internal 
language, which similarly is larger (semantically; syntactically it's 
sexprs).  What combination is more appropriate depends on the language 
and the compiler implementation.
Right, we agree: it is not 'core language' I disagreed with, it is 
'smaller core language'.  And we also agree that smaller/larger depends 
on the eventual application.  But 'smaller core language' is so 
ingrained as "conventional wisdom" that I felt compelled to offer 
evidence against this bit of folklore.

Jacques