I want to build a Data.Map where the keys are strings, and the values are lists of strings.

In Python, collections.defaultdict(list) makes this pretty straightforward. It gives a hash table ("dict") that has values that default to an empty list, since list() produces an empty list. More info here: https://docs.python.org/3/library/collections.html#collections.defaultdict

Is there an equivalent in Haskell?

Thanks!

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