dict

A hash-map style dictionary built in Dune.

dict is a generic dictionary from text keys to values of type V. It keeps keys and values in insertion order and stores them in parallel arrays, so the behavior is simple and deterministic across backends.

Use Dict<V> when you need a mutable string-keyed map with explicit optional lookups. set inserts or overwrites, get returns Maybe<V>, and keys and values return fresh arrays in insertion order. copy() creates independent dictionary structure but copies generic values shallowly, following Dune's normal value semantics.

import dict;
import maybe;

scores: dict.Dict<int> = dict.Dict.new();
scores.set("ada", 10);
scores.set("grace", 7);
scores.set("ada", 12);

print(scores.get("ada").value_or(0));
print(scores.contains("grace"));
print(scores.keys().len());

Auto-generated from stdlib/dict.dn by tools/gen_stdlib_docs.py.

record Dict<V>

A small associative collection mapping text keys to V values.

The first iteration keeps keys as text and stores entries in two parallel arrays, so lookups are linear. That is simple, predictable, and identical across backends; hashing can come later without changing this API. Generic over the value type V; keys are always text.

Methods:

  • fn new(): Dict<V> — Construct an empty dictionary. — e.g. d: dict.Dict<int> = dict.Dict.new(); d.len() // 0
  • fn set(key: text, value: V): unit — Insert or overwrite the value for key. — e.g. d: dict.Dict<int> = dict.Dict.new(); d.set("a", 1); d.get("a").value_or(0) // 1
  • fn get(key: text): maybe.Maybe<V> — Look up key, returning Present(value) or Absent. — e.g. d: dict.Dict<int> = dict.Dict.new(); d.get("missing").value_or(0) // 0
  • fn contains(key: text): bool — True when key has an associated value. — e.g. d: dict.Dict<int> = dict.Dict.new(); d.set("a", 1); d.contains("a") // 1
  • fn remove(key: text): bool — Remove key; returns whether a value was actually removed. — e.g. d: dict.Dict<int> = dict.Dict.new(); d.set("a", 1); d.remove("a") // 1
  • fn len(): int — The number of key/value pairs stored.
  • fn is_empty(): bool — True when the dictionary holds no entries.
  • fn clear(): unit — Drop all entries, leaving an empty dictionary.
  • fn copy(): Dict<V> — A shallow copy with fresh key/value arrays. — e.g. d: dict.Dict<int> = dict.Dict.new(); d.set("a", 1); d.copy().len() // 1
  • fn keys(): [text] — A copy of the keys in insertion order. — e.g. d: dict.Dict<int> = dict.Dict.new(); d.set("a", 1); d.set("b", 2); d.keys()
  • fn values(): [V] — A copy of the values in insertion order. — e.g. d: dict.Dict<int> = dict.Dict.new(); d.set("a", 1); d.set("b", 2); d.values()