Re: RFC: Should Data.IntMap.Strict be value-strict in the function arguments or the map itself

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I believe

delete undefined Nil

does not terminate with current definition, but would terminate if the explicit seq would not be present.

Good point.

I think option 2 is bad as it gives users no way to know which functions are strict in their value argument without knowing the implementation or us documenting every function with the strictness properties. We could do the latter but the API would be simpler if we just said that all functions are strict in their key and value arguments.

This is even a problem of current API. Although most of the functions are strict in keys, it is not mentioned at any place in the documentation. You are right that option 1 is easily explained and documented. Cheers, Milan