[Haskell-cafe] Rewriting a famous library and using the same name: pros and cons

Gregory Crosswhite gcross at phys.washington.edu
Wed Jun 23 21:05:20 EDT 2010

On 6/23/10 8:06 PM, Duncan Coutts wrote:
> Consider an example where we want to avoid using two versions of a dependency:
> The htar program depends on the tar and zlib packages. The tar and
> zlib packages depend on bytestring. Both tar and zlib export functions
> that use the type ByteString. The htar program takes composes
> functions from the two packages together, passing a bytestring from
> one to the other.

Okay, I hadn't considered this, though it seems like the real problem in 
this situation is that someone violated the package version policy:  if 
tar is upgraded to use a newer, incompatible version of bytestring, then 
it should have an appropriate version bump that causes htar to ignore 
the new version and use the older version instead.

I am getting the impression from these discussions that what we really 
need in the long term to solve a lot of these problems is to enforce the 
package versioning policy.


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