REPL

Meta Commands

Built-in REPL subcommands

The Notch REPL ships with a small set of built-in commands accessible by name at the prompt.

Built-in commands

Command	Purpose
help	Show available commands.
exit	Quit the REPL.
clear	Clear the screen.
logs	Show recent log output.
reset	Wipe the runtime and start fresh.
history	Show input history.
save <FILE>	Save session inputs to a file.
write <FILE>	Toggle live recording of successful evaluations.
load <FILE>	Read and execute a Notch file against the live runtime.

Type the command name at the notch > prompt and press Enter. save takes a file path argument, e.g. save mySession.notch.

Tab completion

Tab completion is wired for the built-in subcommands above. Identifier completion (your own bindings and JVM types) is planned.

History

The REPL keeps a command history that persists across sessions in ~/.notch_history. Use the up/down arrow keys to navigate, or type history to see the full buffer with line numbers. Use save <file> to write a polished version of the session to a .notch file (subcommand invocations like history and save are filtered out so the resulting file is runnable).

Session recording

save and write look similar but capture different things:

save <file> walks the whole input history and writes it to <file>, filtering out meta-command invocations (help, clear, save, etc.) so the resulting file is runnable notch source.
write <file> toggles live recording: every successful evaluation after the first write is appended to <file> until you type write again with no argument. Nothing is filtered. Only one write session can be active at a time.

Use save to snapshot a polished session for re-running. Use write to capture a live coding sequence as you type it.

Syntax highlighting

The REPL colorizes input in real time. Tokens map to colors via the terminal's color palette:

booleans and other constant keywords - constant color
identifiers - variable color
integers - number color
strings - string color
type keywords (e.g. int) - type color

Error display

Parse and runtime errors are rendered with a file location and a caret pointing at the failing token:

notch > 1 +
[notch-repl:1:5]
  1 + 
      ^
unexpected end of input