Hashes

Mutable key-value maps. Type is hash.

Syntax

user: hash = { name: "Echo", active: true };
name: str = user["name"];
user["active"] = false;

Example

user: hash = { name: "Ada", active: true };
user["role"] = "admin";
say(user);
say(user.keys());

{"name": "Ada", "active": true, "role": "admin"}
["name", "active", "role"]

Notes

• Literal keys: identifiers or string literals. Bare identifiers become string keys.
• Runtime indexing requires a string key.
• ensure() sets a default if missing; returns the current value either way. Common for counters and buckets.
• take() and take_last() mutate the hash.
• mapValues(f) returns a new hash with the same keys. filter(f) keeps entries where f(value) is true.
• Iteration order is insertion order; mapValues / filter preserve it.
• A hash bound with const is frozen; field assignment and mutating methods abort.
• Destructuring: { id: int, name: str } = user;. Missing keys abort. Extra keys are ignored (unless the type is exact).

Common Mistakes

• Non-string keys at runtime
• Expecting a missing key to return null (it aborts)
• Forgetting that take() removes the key

Current Limitation

• Runtime indexing: string keys only.
• Key and value types are not generic.

See Also

• Built-in Methods
• Type Aliases
• Hash Usage