Re: [Haskell-cafe] wanted: Function to break circular data dependencies

On Tue, May 6, 2014 at 11:38 AM, Chris Warburton wrote:

Job Vranish writes:

...

I've often found myself wanting a function like this. It would make certain kinds of knot-tying/cycle detection _much_ easier.

Is there any reason why this function can't/shouldn't exist?

This makes me think of the more widely-known 'parallel OR' operator, which evaluates its arguments in parallel and returns whichever finishes evaluating first.

This operator cannot be implemented in Lambda Calculus, but it can in Haskell (via threads). Unfortunately Googling for 'haskell "parallel or"' brings up sentence fragments ('...parallel or concurrent...') rather than a parallel or implementation.

Perhaps you are looking for 'unamb' [0]? Erik [0] http://hackage.haskell.org/package/unamb