[Hat] Installing Hat for _both_ ghc and nhc98

[Malcolm Wallace]

Martin,

> What is the best way to install Hat for both ghc and nhc98?

I would recommend unpacking the source tarfile twice, and building
each version in a separate tree.  (In theory it should be possible to
build in the same tree, but at the moment there are clashes between
.hi files from ghc and nhc98.)

> However, it seems that the hat binaries are built differently when
> building for ghc and nhc98.
> 
> Which set of binaries should I choose?

The stand-alone programs (hat-trans, hat-observe, hat-trail, etc) are
built by either ghc or nhc98, which is why they differ.  For hat-trans,
the ghc-built version runs faster than the nhc98-built version, but
the nhc98-built version uses less heapspace.  For the browsing tools,
I don't think it really matters which version you choose - they run
at about the same speed when built by either ghc or nhc98.  (However,
I have noticed that using ^C to interrupt a list of equations in
hat-observe only seems to work in the nhc98-built version.)

Obviously, the compiler-specific `hat' packages (containing libHShat.a,
and some .hi files) must both be installed.

Regards,
    Malcolm