Proposal: Performance improvements for Data.Set

[tibbe]

Following on from ticket #4277 here is a similar patch for Data.Set.

This proposal provides a patch that improves performance for many parts of the API. Three standard techniques are applied to the code:

• Worker/Wrapper transformations of recursive functions with constant arguments (aka. the static argument transformation).
• Explicit inlining of wrapper functions.
• Explicit strictness of keys to functions.

Three complementary, but orthogonal patches are provided.

• Add a testsuite, with  coverage data (currently 51% of top level functions, and all core functions).
• Add a micro-benchmark suite based on Criterion, for empirical evidence of improvements to each function.
• The optimization patch itself.

All 3 patches should be applied, under this proposal.

The  benchmark results are relatively clear:

32% faster on OS X 10.5.8 on 2 GHz Core 2 Duo

The consideration period is 3 weeks (before ICFP).

Work carried out over 28/29th August, 2010 in Utrecht, NL, by Johan Tibell and Don Stewart.

[milan]

Applied.