Re: Crytpo for nhc

18 May 2003

      Malcolm,

Thanks for this. I'm restructuring the Crypto libraries so that it will
contain Crypto.Modes, Crypto.DES, Crypto.Blowfish etc. The current Blowfish
should work with nhc. When I get the chance, I'll see if I can restructure
DES but it's not top of my priorities at the moment.

[Dominic Steinitz
----- Original Message -----
From: "Malcolm Wallace" 
To: "Dominic Steinitz" 
Cc: ; 
Sent: Tuesday, April 29, 2003 2:33 PM
Subject: Re: Crytpo for nhc
...
"Dominic Steinitz"  writes:
...
I have been trying to write a Crypto library and so far it works with
ghc
and hugs.
Am I right in thinking I am going to struggle with nhc? It uses Word8
and
Word64 heavily. For example, cipher block chaining relies on xoring
Word64.
The things you mention are not a particular problem for nhc98.
The only problem I encountered in the Crypto.hs code is that its use
of the type class machinery is not Haskell'98 compliant.
instance Bits [Bool] where ...
is illegal in Haskell'98, because an instance head must be either a
simple type name, or a type constructor applied to only type variables.
(See the Report section 4.3.2)  If ghc and Hugs permit this, then it is
a non-standard extension to the language.
Unfortunately, I don't immediately see an easy way to convert this
construction into something more amenable.
Regards,
    Malcolm