Skip to main content
Version: 3.x (unreleased)

Toolchain Management with Mops

Mops simplifies toolchain management for Motoko projects, allowing you to specify exact versions of each tool in the mops.toml file for each project.

When you run mops install command, Mops will install the specified version of each tool.

Available tools​

  • moc - Motoko compiler
  • wasmtime - Wasmtime runtime (used by mops test --mode wasi)
  • pocket-ic - PocketIC replica (used by mops bench and mops test --mode replica)
  • lintoko - Extensible linter for Motoko (https://github.com/caffeinelabs/lintoko)
  • wasm-opt - Binaryen Wasm optimizer (used when [optimize] is set)

Specifying tool versions​

Option 1: Use mops toolchain use command​

You can use mops toolchain use command to install specific tool version and update mops.toml file.

mops toolchain use moc 0.10.3
mops toolchain use wasmtime 16.0.0
mops toolchain use pocket-ic 12.0.0
mops toolchain use lintoko 0.7.0
mops toolchain use wasm-opt 131

No need to run mops install when you use mops toolchain use command.

Option 2: Edit mops.toml file​

You can manually edit mops.toml file to specify exact versions of each tool.

[toolchain]
moc = "0.10.3"
wasmtime = "16.0.0"
lintoko = "0.7.0"
pocket-ic = "12.0.0"
wasm-opt = "131"

You need to run mops install command when you edit mops.toml file manually.

pocket-ic versions​

pocket-ic is the one tool with a default: if [toolchain] has no pocket-ic entry, mops test --mode replica and mops bench download and run 14.0.0. The default is a fixed constant baked into the CLI, never a "latest" lookup, so warming the cache ahead of time (in a Docker image build, for example) is enough to keep later runs off the network entirely.

Any version from 9.0.0 up can be pinned, latest included. Mops keeps no list of blessed versions — as with moc, wasmtime and lintoko, the version you pin is the version you get.

Pins below 9.0.0 are rejected with a migration message. They worked in Mops 2.x through a second, legacy PocketIC client, which 3.0.0 removed; without the check, upgrading with an old pin would fail with an opaque timeout from the client instead. Run mops toolchain use pocket-ic 14.0.0.

Option 3: Use explicit file paths​

You can also specify file paths to toolchain binaries. This is useful when building a tool from source. File paths must start with /, ./, or ../.

[toolchain]
moc = "./tools/moc"

or

[toolchain]
moc = "/usr/local/bin/moc"
lintoko = "../custom-lintoko/bin/lintoko"

Toolchain management commands​