$ show caffeinelabs/motoko-base
This repository is the Motoko Base Library, a standard library for the Motoko programming language targeting the Internet Computer platform. It provides fundamental types, data structures, and utilities for building smart contracts (canisters). The library includes purely functional collections (List, Trie, Deque), mutable containers (Buffer, HashMap, TrieMap, Stack), red-black tree based ordered sets and maps (OrderedSet, OrderedMap), fixed-width integer types (Int8-64, Nat8-64), Float, Text, Principal, and low-level IC APIs (ExperimentalCycles, StableMemory, CertifiedData, Timer, Random). The code is well-documented with examples and complexity annotations, and includes a comprehensive test suite using the mo:matchers framework. However, the README explicitly states this package is superseded by the official dfinity/motoko-core package, indicating migration is recommended. Some duplication exists between OrderedSet and OrderedMap (shared RB-tree logic), and several deprecated functions are present. The repository is in maintenance mode with periodic updates for compatibility, but active development has shifted to the core package.
The LLM identified 3 files worth highlighting for reuse:
A self-contained resizable array (ArrayList) implementation with a comprehensive API including functional combinators (map, filter, fold, zip, partition, chunk, groupBy, flatten), stable bottom-up merge sort, KMP substring search, capacity management (1.5x growth, shrink below 1/4), and binary search. Every function is documented with runtime and space complexity. The module is isolated (imports only Prim) and could be extracted into another Motoko project with minimal modification.
A red-black tree based ordered set implemented using a functor pattern (class Operations<T>, factory Make<T>). Provides union, intersect, diff, isSubset, fold, map, filter, and validation helpers. The internal RB-tree logic (balancing, insertion, deletion) is shared verbatim with OrderedMap.mo, which is a maintenance risk but demonstrates correct implementation of a classic data structure. The module is self-contained (imports only base types and Iter) and the functor pattern allows reuse with any comparable type.
A purely functional hash-array mapped trie (HAMT-like) with immutable key-value mappings. Supports put, get, remove, merge, diff, join, disj, fold, filter, mapFilter, and 2D/3D variants. Includes a Build module for deferred query construction. The implementation uses precomputed hashes and a leaf/branch structure with max leaf size 8. It demonstrates non-obvious skill in functional data structure design and is reusable in any Motoko project needing persistent maps.