Documentation for trackUse/trackChange/trackAllow is very unclear

[ezyang]

I was looking for a polymorphic version of want, and I accidentally tried to use trackUse (apparently, I'm supposed to use apply!)

[ndmitchell]

Yes, the track functions are still evolving, better docs is a must (and perhaps better semantics) - apply is what you are after.

[ezyang]

Similarly, I think the Development.Shake.Rule would benefit from more guidance on how the pre-canned file operators can be reimplemented for custom rules. Or maybe it should have polymorphic versions of the operators.

[ndmitchell]

When you say precanned operators, do you mean things like %>, or things like traceUse, or both? Agreed, Shake.Rule should probably have some simple file rules as a demo.

[ezyang]

Also things like "need".