containers VS relude

"Make invalid laziness unrepresentable" means you should use strict versions of container types instead of lazy ones. However, for better or for worse, sometimes the "strict version" of a data type is not actually a strict data type, it's just a strict API to the lazy type. Examples include Data.Map.Strict (not Data.Map or Data.Map.Lazy) or Data.HashMap.Strict (not Data.HashMap.Lazy) (sadly there is no Data.Sequence.Strict but perhaps there will be one day).

Indeed it's rather subtle. See https://github.com/haskell/containers/issues/752 for more discussion on the matter. Nonetheless, I believe it is "spine strict" in the sense that thunks for all values always exist, even if the spine that holds them can be rearranged due to laziness.

Note that the list index operator has O(n) complexity. Ideally you'd want to use something like Seq from the containers package

Edison and containers both have sequence types that support efficient, cons, snoc, viewL, viewR, append, map, and length.

containers

Calling linked lists Haskell's "primary data structure" seems off-base to me. Yes, there's String, yes, there's built-in syntax for List... but there's also everything in containers, and vector is pretty easy to use in practice, though it would probably be good for more learning material to mention it more prominently.

Haskell has much more sophisticated immutable data structures, you can find them in the "containers" package: https://hackage.haskell.org/package/containers

I asked this on the libraries mailing list but thought posting here would bring in potentially more responses. I made a recent change to the behaviour of lookup and find (see here for more details: https://github.com/haskell/containers/pull/800).

Rust has nothing on Haskell. containers, which might as well be considered part of the standard library, has been out for almost 14 years and is still 0.x

I've also hoped that the "standard library" (i.e. Prelude) should be redesigned. I just found relude which looks very promising.

Project to look at is: https://github.com/kowainik/relude.

Another good practice to prevent runtime exceptions is to avoid partial functions like head and tail. One way to ensure that one doesn't accidentally slip in is to use an alternative prelude (e.g. relude) that doesn't export them by default. Another alternative is to use hlint to warn about them (and then import their safe counterparts instead).

That note is wrong, it is only a problem if the function input has a large cardinality. I opened a PR to fix this: https://github.com/kowainik/relude/pull/389

And relude.