[dllthomas]

I think that's only a part of it. I think that it's also the case that the Haskell ecosystem has more breaking changes at the root of diamonds in the dependency graph - which isn't something a build tool can solve (or at least isn't something any build tool does solve).

[sjy]

In my experience the dependency graph often has many more nodes as well. I'm not sure if this is because Haskell code is especially reusable or Haskell developers are especially lazy.

[freyrs3]

There is an ambient culture of code reuse at a level I don't see elsewhere, that's one of Haskell's strength's in my opinion. Though it does make certain packaging problems more difficult.

[dllthomas]

High levels of abstraction and well defined edges mean more opportunities for reuse, which probably contributes to both.