Fwd: [Haskell-cafe] Data.Tree.Zipper in the standard libraries

Isaac Dupree isaacdupree at charter.net
Wed Jun 4 14:26:06 EDT 2008

Iavor Diatchki wrote:
> Hi,
> If this is the consensus, than people that feel this way should write
> a document describing the new process so that we know how to
> contribute code.

+1.  unfortunately, I'm not volunteering today

> - what is a "core" package
>   Perhaps, a package that is distributed with GHC?

Evidently not -- mtl is probably considered a core package, and, it's 
not distributed with GHC.  Perhaps, a package that is maintained by 
libraries at haskell.org?

> - what constitutes a "significant" change
>   Not sure how to define this.  I would be weary of changes to the
> existing functions/types in the APIs of existing modules.  But adding
> extra functionality?  Especially, if---like in the case of
> Zipper---the implementation can be more or less computed from an
> existing definition in the package (I am referring to the fact that
> the zipper is the derivative of Tree, for details you can look at
> Conor's paper).
> - what makes code "proven"
>   Again, not sure how to define this.  The code for Zipper has QC
> tests that cover it 100%, according to HPC.

Proven to be a useful interface, more than proven to be bug-free[*], 
IMHO.  It's easier for us to maintain a package by perfecting its 
documentation, implementation etc. as a community; but harder to explore 
large design spaces when an existing solution comes to be felt as 
inadequate for the purposes it's used for.

[*] of course you can't *prove* anything to be bug-free, let's say 
"demonstrated not to have too many fatal bugs" :-)


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