GHC internals

[Simon Peyton-Jones]

That's not really true though.  The compiler implements beta-reduction; and inlining; and directly implements the "Push" rules in exprIsConApp_maybe. 

S

| -----Original Message-----
| From: Richard Eisenberg [mailto:eir at cis.upenn.edu]
| Sent: 29 April 2013 14:30
| To: Simon Peyton-Jones
| Cc: 'Norman Ramsey'; ghc-devs at haskell.org; Simon Marlow
| Subject: Re: GHC internals
| 
| It's true that the document in GHC doesn't include operational
| semantics, but that's because GHC doesn't ever really implement a
| concrete operational semantics for Core, at least that I'm aware of.
| There are various places that a certain operational semantics is
| assumed. However, I don't think there's one place that really states the
| semantics in any concrete way. The goal of the document you attached is
| to have an easy-to-read and easy-to-maintain version of Core, with a
| direct connection to the implementation. With the operational semantics
| never stated, including those rules seemed to go against that goal.
| 
| That said, it wouldn't be hard for me to imagine an operational
| semantics and add it to the document -- I just don't know how I would
| check my imagined version against the implemented one.
| 
| Richard
| 
| On Apr 29, 2013, at 8:38 AM, Simon Peyton-Jones <simonpj at microsoft.com>
| wrote:
| 
| > Norman
| >
| > |    - Is there anything published about the implementation of GHCi?
| > |      Or perhaps something on the Developers' Wiki that explains how
| it works?
| >
| > If you mean the details of bytecode compilation and the bytecode
| interpreter, I'm really not sure that there is.  That's bad; there
| should be. I'm ccing Simon M in case he knows of something.
| >
| > |    - What is the best paper (or papers) to consult on the semantics
| > |      of GHC core?
| >
| > Many of these papers
| > 	http://research.microsoft.com/en-us/um/people/simonpj/papers/ext-f/
| > give syntax, static semantics, and operational semantics of Core.
| >
| > Moreover, Richard Eisenberg has developed a specification of the Real
| Core in GHC, kept in the source tree in docs/core-spec
| >
| > I enclose a typeset version.
| >
| > Sadly it doesn't include operational semantics, but I don't think
| that'd be hard to add, would it Richard?  The papers on the above link
| give several versions of the operational semantics, which is largely
| straightforward.
| >
| > Simon
| > <core-spec.pdf>