Proposal: Value strict versions of containers

[Edward Z. Yang]

Excerpts from Milan Straka's message of Sun May 22 06:50:07 -0400 2011:
> - the types Data.IntMap.IntMap, Data.IntMap.Lazy.IntMap and
>   Data.IntMap.Strict.IntMap should be equal -- so I can use strict
>   methods on IntMap someone else created with lazy methods. That is
>   simple in absence of type classes.

Comment: This would mean you would get no static assurances against
mixing up a strict IntMap with a lazy IntMap; for all intents and purposes,
this is equivalent to implementing strict versions of all functions on top
of a lazy data type.

Cheers,
Edward