Proposal: undeprecate Data.ByteString.Lazy.Builder

Dag Odenhall dag.odenhall at
Wed Sep 4 13:53:40 CEST 2013

…and deprecate Data.ByteString.Builder. Why?

   - It would be more consistent with Data.Text.Lazy.Builder
   - It does in fact build lazy bytestrings
   - But most importantly, Data.ByteString.Builder is not available in the
   version shipped with current GHC or Haskell Platform!

I fear this last point will force a lot of ugly #ifdefs for code that wants
to support a range of versions in the future. A common goal is to support
the last three major GHC versions. This would mean we can't start to use
Data.ByteString.Builder unconditionally before GHC 7.12, and neither can we
use Data.ByteString.Lazy.Builder unconditionally if it is dropped before
that or DEPRECATED warnings are added and we want to build without warnings.

On the other hand, if you want to support three GHC versions back it still
means you can't use Builder without blaze-builder before 7.10. Perhaps we
should just pretend that Builder never made it into 7.6, because 7.8 will
be the first version with Data.ByteString.Builder?

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