10. Tooling day-to-day

The edit loop around a living document: fmt, set, diff, and the repl.

Before you start: Imports and namespaces

Once a document exists, most work is small edits. wcl fmt --in-place rewrites to canonical form (comments and blank-line groupings survive). wcl set file.wcl path value updates one field in place, following the import chain to the file that declares it — the value is parsed as a WCL expression, so quote it from the shell. wcl diff old new compares the *evaluated* documents, so a formatting-only change is an empty diff.

For exploration, wcl repl file.wcl gives you a prompt whose identifiers resolve against the file's top-level fields — the quickest way to poke at expressions before committing them.

§ 1Exercise: One full edit loop

Take the services file from lesson 5, change a port with wcl set, and inspect the change with wcl diff.

cp config.wcl config.new.wcl
wcl set config.new.wcl services.api.port 8443u32
wcl diff config.wcl config.new.wcl
wcl fmt config.new.wcl --in-place
wcl check config.new.wcl