[dscrd]

http://www.paulgraham.com/know.html

Learning Haskell adds to the mass of things you know, and the volume of that mass determines the level of your general expertise.

You asked for tangible things, but it's harder to see what those may be. Perhaps your perception will be enhanced: perhaps you will better see and care about side-effects, opportunities for pure functions, etc.

I don't think any learning effort that leads to increased knowledge can be a waste of time.

[AnimalMuppet]

In absolute terms, no, learning is never a waste of time. In a world with limited time, though, everything has its opportunity cost. The time spent learning A could have been spent learning any of B through Z.

So: "Is Haskell worth learning?" Yes, certainly. "Is learning Haskell the best use of my limited time for such activities?" That's a much harder question.

(And it doesn't have to be the best use of your time. It could be close enough that it's not worth the time looking for something better.)

[dllthomas]

I think the opportunity cost is meant to be weighed in any question of "is X worth it?"

That said, I appreciate your calling it out specifically (even if I'd have used other words), as that is absolutely the real question.

My answer, I'm sure you'd guess, is "yes" - but certainly I agree that it's harder than the same question but ignoring the costs :-P