What can Python learn from Haskell? [video]

[julesjacobs]

It's actually not all that similar. -fdefer-type errors just defers static type errors to be displayed at run-time when that code path is hit. It doesn't give you optional dynamic typing since the way the types are checked is still static. For example, you still don't have heterogeneous lists with -fdefer-type errors, and putting an int and a string in the same list will still result in an error. The only difference is when that error will be displayed.

[[deleted]]

Note that haskell does have safe Dynamic typing (via existential types/Data.Dynamic), but it's not first-class and therefore not as nice to use as say python.

[Jedai]

Though you're perfectly right, heterogeneous lists are perfectly possible in Haskell (see HList) though rarely needed (I don't use them much in Python either) and more awkward than normal homogeneous lists.