map

Vary the value of m get k.

Grab a value out of Map if it's present. Otherwise evaluate a value to be placed at that key in the Map.

As with Map.updated, but resolve a collision with f. The first argument is guaranteed to be from m1.

Collect only elements with matching keys, joining their associated values with f.

Like intersectWith, but tell f about the key.

Exchange keys of m according to f. Result may be smaller if f maps two or more Ks to the same K2, in which case the resulting associated value is an arbitrary choice.

Union, resolving collisions with f, where the first arg is guaranteed to be from m1, the second from m2.

Like unionWith, but telling f about the key.

Covariant over the value parameter, where plus applies the Last semigroup to values.

Map union monoid, unifying values with V's append.