REPL

The interactive Read-Eval-Print Loop starts when mac is run with no arguments.

$ mac
|> print "Hello, Mac!";
Hello, Mac!
|>

Prompt

Multi-Line Input

Open braces, brackets, or parentheses automatically enter multi-line mode. The REPL waits for all delimiters to close before executing.

|> var greet = (name) -> {
..     return "Hello, " + name;
.. };
|> print greet("Mac");
Hello, Mac

Keyboard Shortcuts

History

Command history is saved to ~/.mac_history and persists across sessions. Each line of multi-line input is stored individually for easier recall.

Auto-Semicolons

Simple expressions without a trailing ; or } get a semicolon appended automatically.

|> print "no semicolon needed"
no semicolon needed

Pasting

Multi-line code can be pasted directly. Newlines in pasted text are processed through the same brace-tracking as typed input.

Commands

Piped Input

When stdin is not a terminal, Mac reads all input as a batch and executes it.

echo 'print "hello";' | mac
# Output: hello