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> Also, if the map has arrays as elements, it will magically create one, like Python's defaultdict. Err, no Go doesn't do that. No insertion happens unless you

• culebron21 11mo ago
  You're right. But it will return something: https://go.dev/play/p/Cz6aeGpURgo https://go.dev/play/p/Cz6aeGpURgo my_map := make(map[int32][]int64) val := my_map[123] val = append(val, 456) my_map[123] = val fmt.Println(my_map) prints `map[123:[456]]` I guess it's convenient compared to Rust's strict approach with entry API. But also, what I found is that golang's subscript returns nil in one case: if the value type is a nested map. my_map := make(map[int32]map[int32]int64) val := my_map[123] val[456] = 789 my_map[123] = val fmt.Println(my_map) output: panic: assignment to entry in nil map
  • HL33tibCe7 11mo ago
    It returns the zero value for all types, including arrays (which is nil). nil is equivalent to the empty array, which is why the rest of the code works as it does.
  • tiltowait 11mo ago
    You can test for existence: val, ok := my_map[123] if ok { ... } https://go.dev/blog/maps#working-with-maps https://go.dev/blog/maps#working-with-maps