This repository contains the implementation of semantics and simple type checker for the book TAPL.

Directory Structure:

• Untyped Arith - implementation of untyped arithemetic expression, corresponding to chapter 3 ~ 4;
• Untyped - implementation of untyped lambda calculus, corresponding to chapter 5 ~ 7;
• SimplyTyped - implementation of simply typed lambda calculus (STLC), corresponding to chapter 8 ~ 10.