Maps

Looking things up by key

A slice is great for an ordered list. But often you want to look something up by a key: the rating for a given walker ID, the price for a given duration. That's a map — Go's dictionary.

The type spells out both halves: map[KeyType]ValueType.

• map[string]int — string keys, int values (walker ID → rating).
• map[int]int — int keys, int values (duration in minutes → price in cents).

This is Swift's Dictionary<Key, Value> — same idea, terser syntax. Keys are unique; assigning to an existing key overwrites it.