Re: base package (Was: GHC 7.8 release?)

On 15/02/13 08:36, Joachim Breitner wrote:

Hi,

Am Donnerstag, den 14.02.2013, 21:41 -0500 schrieb brandon s allbery kf8nh:

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On Thursday, February 14, 2013 at 8:14 PM, Johan Tibell wrote:

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On Thu, Feb 14, 2013 at 2:53 PM, Joachim Breitner 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/b7f80066a03fd296950e0cafa227... 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