How can I get all pairs of values from an association with elements key->list

Question

I have an association of the form

ds=<|key1 -> list1, key2 -> list2,... ,keyn -> listn|>

I would like a simple way to map a function to all pairs {a, b}, where a is a key and b is element of the list associated with key a. I have found several brute-force methods but is seems that there should be something akin to

f /@ ds

This only feeds f with the lists one by one.

I can do it this way:

g[a_, b_] := h[a, #] & /@ b

Flatten@KeyValueMap[g, ds]

Is there a more compact way?

Answer 1

KeyValueMap:

ds = <|key1 -> list1, key2 -> list2, keyn -> listn|>;

KeyValueMap[f] @ ds

$\ ${f[key1, list1], f[key2, list2], f[keyn, listn]}

ds = <|key1 -> {x1, y1}, key2 -> {x2, y2}, keyn -> {x3, y3}|>;

KeyValueMap[f[#1, #2[[1]]] &, ds]

$\ ${f[key1, x1], f[key2, x2], f[keyn, x3]}