Can't install Criterion package on ghc ..

[Simon Peyton-Jones]

John

| I'm not the original reporter, but I can confirm that I am able to
| install Criterion-0.5.0 with ghc-6.12.1 on OSX 10.6.  One datum,
| anyway.
| 
| The problem isn't with criterion itself, but with vector-algorithms.
| The vector library relies heavily on type families, which have dodgy
| support in ghc-6.10.

To be honest, the support for type families is equally dodgy in 6.12.  I'm amazed how well it works! As you may know, I've been claiming to be in the middle of rewriting the type inference engine, with the goal of cleaning all this up, for some months now, distracted by ICFP paper writing, WG2.8, ICFP reviewing, and now being stuck in Tokyo unable to get home.

Bottom line: adding this missing type signatures is a good move regardless. I'm glad that seems to fix it

If you were able to submit a Trac ticket with a small reproducible test case showing a program that compiles ok with 6.12 but fails with 6.10, that would really help me to make sure the new implementation does the job. 

Simon