Type inference fails in extensions. about fsharp-typeclasses HOT 3 CLOSED

It was fixed in the alternative version: 
http://code.google.com/p/fsharp-typeclasses/source/detail?r=cbecd23850c8c11c5dea
9285ec0173a1040773bc&repo=staticmethods

Looks like 4 types in the "or expression" are needed.

[deleted comment]

It appeared to be fixed in 
http://code.google.com/p/fsharp-typeclasses/source/detail?r=6961c6dd264855ee6d1d
9a10f18177316829a31d but then some other code stopped being inferred (see 
https://code.google.com/p/fsharp-typeclasses/source/diff?spec=svn6b10b6882aedcbd
4831ab98084c93310650bfa00&r=6b10b6882aedcbd4831ab98084c93310650bfa00&format=side
&path=/Script.fsx).

It definitely need 4 parameters in the overload resolution, this was possible 
thanks to F# 3.0 in rev. 118 
https://code.google.com/p/fsharp-typeclasses/source/detail?r=03d7ccd5c04a9e840ac
db8d495ab037575d8eedf