How to handle Maps inside Maps

[AleDema]

If I have a scenario like this

Map.new<Principal, Map.Map<Text, Nat>>()

What is the best way to read and write to nested maps?

[ZhenyaUsenko]

Firstly, I'd like to suggest an alternative solution which can work in some situations - create custom hash utils (Principal, Text)

let pthash: Map.HashUtils<(Principal, Text)> = (
  func(key) = (Prim.hashBlob(Prim.blobOfPrincipal(key.0)) +% Prim.hashBlob(Prim.encodeUtf8(key.1))) & 0x3fffffff,
  func(a, b) = a.0 == b.0 and a.1 == b.1,
  func() = (Prim.principalOfBlob(""), ""),
);

and change your map type to

Map.new<(Principal, Text), Nat>()