Transpile

Compile an ilo program to JavaScript or Python source. Use this when you need to run ilo logic in a JS or Python runtime — browser, Node, embedded Python, or any non-ilo host.

Targets

Shell

ilo build file.@ --emit js -o file.js          # ES module
ilo build file.@ --emit python -o file.py      # Python 3.8+

Same ilo build subcommand as the native AOT path; the --emit flag chooses the target.

What gets emitted

• JS: ES module with arrow-function bodies, kebab-case → camelCase rename (make-id → makeId), Result encoded as ["ok", v] / ["err", e] tuples, records as plain objects with _type key. Builtin mapping: len → .length, abs/min/max/flr/cel/sqrt → Math.*, prnt → console.log, jdmp/jpar → JSON.stringify/parse, rnd → Math.random(), list append → spread.
• Python: idiomatic Python 3 source with type hints. Same Result-as-tuple shape. Records as @dataclass.

Limitations

The transpiled output is not a full ilo runtime — it covers the canonical surface (functions, prefix expressions, guards, match, Result, records, lists, maps, common builtins). Features that don’t have a clean host equivalent are deferred:

• JS: file I/O, defer/errdefer, World/capabilities, tagged sum-type match patterns, generic monomorphisation (best-effort), full builtin coverage
• Python: pattern-match arms that depend on ilo-specific match semantics, World/capabilities

For production code that needs full ilo semantics, ship the native binary (ilo build) or run via JIT (ilo run --jit).

When to use it

Use case	Reach for
Browser script	--emit js
Existing Python codebase calling ilo	--emit python
Cross-platform native binary	native AOT (no --emit)
Hot numeric loop on the server	ilo run --jit
One-off CLI invocation	ilo run

Related

• ilo build — native AOT compile (default target)
• Engines reference — VM, JIT, AOT comparison