roci check
roci check reads a sketch and says what is wrong with it, without running it or opening a window. It says every mistake it finds in one go, not only the first, each with the line, what went wrong in plain words and a line that would work.
roci check the sketch in this folder
roci check sketch.roci one file
roci check my-sketch a folder: every .roci file in it, read as one program
If all is well it says so, and it exits with 0. If something is wrong it exits with 1, and with 2 when a file could not be read, so a script or a pipeline can use it.
Options
roci check --types also say what each name in the sketch holds
roci check --errors json print every message as a line of JSON, for editors and other tools
roci check --tree also print the syntax tree, for people working on the language
--types is a good way to see what rocinante worked out for you: a number, text, a list of records with these fields. Nobody writes types in rocinante, but they are there, and a mistake such as using a number where text is wanted is found from them.
What it is for
roci run finds the same mistakes, and when you save a sketch that has one the window keeps running the last good version under an error band. roci check is for when you want the answer without a window: in an editor, in a script, or on a computer with no screen.
Every message is listed on the messages page.
See also roci test, which runs the checks you write, and roci fmt.