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

[Jacques Carette]

On 22/11/2012 11:52 AM, Brandon Allbery wrote:
> On Thu, Nov 22, 2012 at 7:56 AM, Jacques Carette <carette at mcmaster.ca 
> <mailto:carette at mcmaster.ca>> wrote:
>
>     On 20/11/2012 6:08 PM, Richard O'Keefe wrote:
>
>         On 21/11/2012, at 4:49 AM, <citb at lavabit.com
>         <mailto:citb at 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

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