Comment by pkal
7 hours ago
If you instantiate it with concrete types, does "(b IntBox) Map(f func(int) string) StringBox" make more sense? You have a collection (in this case Box) containing values of type T, a function that maps values of type T to type U, and if you apply that function to all elements in that collection you get a collection of type U.
Only they are not using a collection and therefore "Map" was a confusing choice for the method name (maybe "To" would have been a better name?).
A one item collection is admittedly a lame one, but it is a collection. Pointers are collections of zero or one items in a sense.
Now, the verb "map" is the traditional name for this operator, but I agree it sounds confusing when the noun "map" is also a collection type. C# and SQL call this Select, if that helps.
Is that really the confusing part? If you had a general collection interface, say Mapper, a Box (i.e. a singleton set) could implement it just as well as a List or a Tree.
I realize that mathematically speaking a singleton set is still a set, but as a programmer who is used to map operations in other mainstream languages, I was expecting some kind of loop in the implementation. It took a few page faults in my brain to realize what's going on.
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