ecko explain, lint and fix

Three tools that read a program and tell you something about it. lint is mechanical; the other two use a model.

ecko lint

ecko lint file.ecko

Reports code that is present but doing nothing:

• dead code after a return, break or continue
• unused imports
• unused variables
• unreachable branches

No model involved, no network. This overlaps ecko check - the split is that check answers "is this wrong?" and gates the run, while lint answers "is this needed?" and never does.

ecko explain

ecko explain file.ecko

Static analysis plus a model, producing prose: what the program does, how it is structured, what stands out. Useful on code you did not write, or wrote long enough ago that it counts.

It reads the program. It does not run it, so it cannot tell you what the program actually did with real input.

ecko fix

ecko fix file.ecko

Takes the errors in a file and suggests a repair. It prints the suggestion; it does not edit your file.

fix also carries mechanical migrations, which do rewrite files and are worth knowing about because they are exact rather than suggested:

ecko fix --migrate-bytes src/       # *_decode -> *_decode_text, net.recv -> recv_text
ecko fix --migrate-exports src/     # the old `export { ... }` block to inline `export`

Those two exist because both changes were breaking and mechanical - the kind where a codemod is more trustworthy than a human doing it by hand across a codebase.

Which to reach for

check, lint and fmt need no key. explain and fix produce mock output without one.