clox

My implementation of the Lox programming language in C, following Crafting Interpreters by Robert Nystrom.

Compiling

Clone the source and run make. The clox executable is created in the build folder.

Running

clox can be run in interactive mode by passing no arguments. An example of interactive mode is shown below

clox> print 2 + 2;
4
clox> fun double(x) {return x * 2;}
clox> print double(2);
4

My implementation of clox uses linenoise to handle terminal interaction. This means the left- and right- arrow keys can be used to edit input, and the up- and down- arrow keys can be used to page through your history.

Alternatively, you can run clox on a file by passing the file name as the first argument, i.e clox my_program.lox.

Differences in my implementation

My implementation differs from the canonical one in a few ways

• Underscores can be used as separator characters in numeric literals
• print is a built-in function instead of a statement and does not append a newline character. print also takes multiple arguments, which are concatenated.
• Added a companion println function which works exactly like print, but appends a newline to the end.

Example programs

Several example programs, most taken from the book, can be found in the examples folder.

Tests

There are some automated tests in test.c which can be run by passing the --test flag to clox. These tests are not exhaustive but cover some aspects of lexing, codegen, and hash tables.