Mops CLI

Opinionated guide for Motoko projects. Covers project config, dependency management, type-checking, building, and linting.

Key Principles

1. No dfx — mops neither invokes nor supports dfx. There is no mops toolchain init, no moc-wrapper, and no mops watch --generate / --deploy. Always pin moc in [toolchain]; every command that compiles requires it. Use the newest moc version. Pin pocket-ic too if you have replica tests, benchmarks, or --check-deploy — with no pin those commands error, naming mops toolchain use pocket-ic 15.0.0. When MOPS_POCKET_IC_URL points at an already-running PocketIC server, no pin is needed and an existing pin is ignored with a warning — do not add one to silence it; unset the variable instead.
2. No mo:base — it is deprecated. Always use mo:core (import Array "mo:core/Array").
3. All config in mops.toml — canisters, moc flags, toolchain versions, build settings.
4. Canister-centric workflow — define all canisters in [canisters]; never pass file paths to mops check. Exception: library packages (no [canisters]) use file paths directly: mops check src/**/*.mo.

Project Setup