A free online compiler textbook by Prof. Douglas Thain at Notre Dame offers undergraduate computer science students hands-on experience building compilers. Available directly online or in print, the book serves as course material for CSE 40243 compilers class and provides practical insight into language design. The textbook teaches compiler construction over one semester, guiding readers through scanning, parsing, semantic analysis, and code generation.

Students learn to translate a C-like language into working X86 or ARM assembly, requiring prior experience in C programming and computer architecture fundamentals. Additional resources include the compilerbook-examples GitHub repository with scanners, parsers, and test cases for each compilation stage. The author encourages pointing students to compilerbook.org for latest updates rather than distributing PDFs locally.

This educational resource fills a gap in accessible compiler education, combining theoretical foundations with practical implementation. The book's modular approach makes complex compiler concepts approachable for undergraduate students.