17 Apr
2012
17 Apr
'12
3:11 p.m.
Dan Burton wrote:
Ever find yourself wanting to generate a tuple of random things? Instances are trivial to write in Haskell 98... Can we add instances like this to System.Random in the random package?
I'm guessing that this was left out because of its surprising side-effect of adding strictness to the first component: If you try to get the value of the second component, the first one is forced. For example, imagine that in randomR the computation for the lower bound on the first component is expensive or bottom, and you only ask for the second component in the calling code. You would really want to use split for this. But not much is known about how to write good random generators with provably good splitting properties. -Yitz