[Haskell-cafe] Are constructors strict?

[Edward Z. Yang]

Hello Daryoush,

That is a good question, and depends on distinguishing between laziness
and nondeterminism.  Suppose I have a normal, lazily evaluated list:

    [1,2...]

There are thunks used in this case, but the end result is fully deterministic:
the next will always be 3, and then 4, and so on.  So thunks don't
give us nondeterminism; we need some other mechanism (whether it's another
list encoding the choices, or a more sophisticated backtracking monad.)

Edward