On 15/02/13 08:36, Joachim Breitner wrote:
Hi,
Am Donnerstag, den 14.02.2013, 21:41 -0500 schrieb brandon s allbery
kf8nh:
On Thursday, February 14, 2013 at 8:14 PM, Johan Tibell wrote:
On Thu, Feb 14, 2013 at 2:53 PM, Joachim Breitner
<m...@joachim-breitner.de> wrote:
I don't think having FFI far down the stack is a problem. There are
lots of pure data types we'd like in the "pure data" layer (e.g.
bytestring) that uses FFI. As long as the I/O layer itself
(System.IO, the I/O manager, etc) doesn't get pulled in there's no
real problem in depending on the FFI.
I think it would be nice, also to other Haskell implementations that
might have not have FFI, to separate the really basic stuff from
pure-but-impurely-implemented stuff. At least as long as it does not
caues trouble.
GHC.Fingerprint does not need to be crippled when it is going to use a
pure hashing; I quickly added some simple fingerpriting found via
Wikipedia that was easier than MD5.
https://github.com/nomeata/packages-base/commit/b7f80066a03fd296950e0cafa2278d43a86f82fc
The choice is of course not final, maybe something with more bits is
desirable.
Remember that fingerprinting is not hashing. For fingerprinting we need
to have a realistic expectation of no collisions. I don't think FNV is
suitable.
I'm sure it would be possible to replace the C md5 code with some
Haskell. Performance *is* important here though - Typeable is in the
inner loop of certain generic programming libraries, like SYB.
Cheers,
Simon
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