March 2014 - Libraries

Alex and GHC 7.8
by wren ng thornton 08 Mar '14

08 Mar '14

Hello, In testing my packages for the impending GHC 7.8 release, I ran into some issues with Alex-generated code. In particular, it looks like the (>=#) and (==#) operators now return Int# instead of Bool, so expressions like if (offset >=# 0#) && (check ==# ord_c) then ... no longer type check. Is this a known issue? Are there any plans to fix it? I'd offer to submit a pull-request, but I'm not familiar with the Alex codebase so that'd take a while -- Live well, ~wren

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Proposal: Explicitly require "Data.Bits.bit (-1) == 0" property
by Herbert Valerio Riedel 08 Mar '14

08 Mar '14

Hello *, Right now, there seems to be no "defined" way to create a zero 'Bits'-value (w/o requiring also a 'Num' instance), that has all bits cleared without involving at least two operations from the 'Bits' class (e.g. `clearBit (bit 0) 0` or `let x = bit 0 in xor x x`). OTOH, introducing a new method 'class Bits a where bitZero :: a' seems overkill to me. However, "bit (-1)"[1] seems to result in just such a zero-value for all 'Bits' instances from base, so I'd hereby propose to simply document this as an expected property of 'bit', as well as the recommended way to introduce a zero-value (for when 'Num' is not available). Discussion period: 2 weeks [1]: ...or more generally 'bit n == 0' for n<0, as it's usually implemented as 'bit n = 1 shift n'

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ANN: time-1.4.2
by Ashley Yakeley 03 Mar '14

03 Mar '14

time-1.4.2 is now available from Hackage. <http://hackage.haskell.org/package/time> This update is one contributed improvement, Safe Haskell annotation, from Omari Norman. Thanks! -- Ashley Yakeley

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