Proposal: Value strict versions of containers

[Edward Z. Yang]

Here is the implementation:

    http://hpaste.org/49733

I'd appreciate sanity checking. The way this works is that if a function is
not mentioned here, we use the lazy version.  All strict functions assume
both maps are strict on input, and are maximally lazy because of this (for
example, "strict" union will not inspect any values, because both input
maps have fully evaluated values.)

Cheers,
Edward

Excerpts from Edward Z. Yang's message of Sat Jul 30 23:43:09 -0400 2011:
> Tallying informal votes, it appears we are +5 in favor of Strict and Lazy
> modules with the same underlying representation, with deprecation of
> strict methods in Data.IntMap.
> 
> I will be implementing this at Hac Phi tomorrow.
> 
> Cheers,
> Edward