[chowells]

Those books define laziness, and provide a couple examples - but they do not teach a programmer how to use it correctly.

Correct use of laziness involves choosing sufficient space invariants, implementing them, and documenting them. This is critical for writing efficient code in Haskell, and rejecting the "everything strict" cargo cult at the same time allows you to recover compositionality.

There was a period of time around 15 years ago, back before core libraries really started to understand this concept, and they would often have updates that silently made things too strict, breaking my code that was using their previous laziness in ways they hadn't predicted.

And it bugs me when I see new resources being set up to train people to write code that prevents my creative uses of their libraries. We should teach people how to write efficient Haskell code that's still Haskell code. It's great that we have so many advanced strictness tools when they're needed. But they shouldn't be reached for before we know if they help.

[doyougnu]

Great! If you could open an issue and perhaps lay out what you would like to see I would be more than happy to add a chapter like this. This book should serve the community and I think you've described a good gap that the book has which we could close with such a chapter.

[chowells]

You're right. I should at least give you an outline for the topic.