moxzi
Skills / moxzi-cli

moxzi-cli

Compiling Motoko locally with the moxzi CLI: build/link/deps/info/cache commands, package resolution via mops or --package, output artifacts (.wasm + .did), required flags, and error diagnostics. Use when compiling .mo files to wasm with moxzi, wiring mo: imports, choosing build flags, or interpreting moxzi build errors. Do NOT use for running the produced wasm (use moxzid-server or moxzi-web), for paid on-chain builds (use moxzi-onchain-builds), or for Motoko language questions.

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Critical rules#

ALWAYS:

NEVER:

The commands#

moxzi build <entry.mo> -o <out.wasm>   # compile locally (the normal path)
moxzi link <unlinked.wasm> -o <out>    # link a --no-link or on-chain-compiled module
moxzi deps <entry.mo>                  # print the upload closure: every file an on-chain build would send, with VFS paths
moxzi info                             # loaded compiler + linker paths, hashes, cache state, exports
moxzi cache path|clear                 # the AOT compiled-module cache

Hello world (complete, works as-is)#

cat > hello.mo <<'EOF'
persistent actor {
  public query func greet(name : Text) : async Text { "Hello, " # name # "!" };
};
EOF
moxzi build hello.mo -o hello.wasm

Expected output shape:

hello.mo -> hello.wasm + hello.did (220356 bytes, 1 file(s), 59 steps, 0.7s)
compiled by ./compiler.wasm (sha256 86ea6a…), moxzi 0.1.0-alpha.1

hello.wasm deploys to the IC as-is (dfx canister install --wasm hello.wasm), runs under moxzid, and runs in a browser via moxzi-web.

Toolchain resolution#

The compiler and linker are wasm files, found in this order:

  1. --compiler <WASM> / --linker <WASM> flags
  2. MOXZI_COMPILER / MOXZI_LINKER environment variables
  3. the search path (a release tarball ships compiler.wasm + linker.wasm beside the binary)

moxzi info reports what was actually loaded, with hashes.

Package resolution#

# preferred: a mops project — nothing to pass
cd my-project        # has mops.toml
moxzi build src/main.mo -o main.wasm

# explicit: like moc --package, repeatable
moxzi build main.mo -o main.wasm --package base /path/to/base/src

--root <DIR> sets what /src maps to (default: nearest ancestor with mops.toml or dfx.json, else the entry file's directory). Error paths are reported under /src.

Flags that matter#

FlagUse
--debugdebug build
--no-idlskip writing the .did
--no-linkstop before linking (feeds moxzi link or an on-chain link)
--timingsper-phase timing
-vforward the compiler's own debug output
--stack-budget <N>scheduler yield ceiling; 0 = canister default (200). Off-chain, raising it is the difference between minutes and hours on large projects — yields are checkpoints, output bytes do not change
--force-gccollect at every message boundary; caps off-chain heap growth at instruction cost (fine locally)
--default-persistent-actorsrewrite bare actor to persistent actor (moc-compatible flag)
--stable-regions, --max-stable-pages <N>, --stabilization-instruction-limit <N>, --measure-rts-stack, --trap-on-call-errormoc-compatible passthroughs
--remote <URL> --canister <ID>build on a compiler canister instead — see the moxzi-onchain-builds skill

Error diagnostics#

Everything is source-located (/src/file.mo:line.col-line.col) with moc's error codes.

SymptomMeaningFix
[M0220] … should be declared 'persistent'bare actoradd persistent, or pass --default-persistent-actors
[M0020] unresolved import mo:foo/Libpackage not resolvablerun in a mops project, or add --package foo <path>
[M0050] literal of type Text does not have expected type Natordinary type errorfix the code; codes match moc's
expression nested too deeply (limit 128) / type nested too deeply (limit 128)machine-generated deep nesting hit the parser depth guardchunk generated expressions/types
entry is module { … }not an error — a library build is a valid buildexpected
validate fails on a --no-link artifactit is unlinked BY DESIGNrun moxzi link first

Quick reference#