PL Interpreters

Self-directed study in programming language implementation, spanning Haskell, Standard ML, and Scheme.

Projects

appel-straight-line/ — Appel's Modern Compiler Implementation in ML, Chapter 1

• straightLineLang.sml — Full interpreter for a straight-line programming language: AST definition, maxargs static analysis, and interpStm/interpExp mutually recursive interpreter with mutable environment threading.
• chap1Exercises.sml — Binary search tree with member, insert, and a valid function implementing "parse, don't validate" via an opaque validTree wrapper type.

haskell-straight-line/ — Same interpreter, ported and extended in Haskell

• Lib.hs — Port using Control.Monad.State for environment threading + an attoparsec parser for the straight-line language.
• LibAlt.hs — Refactored version using a modular monad transformer stack (WriterT for print output, StateT for environment, ExceptT for errors).

parser-from-scratch/ — Hand-rolled monadic parser

• Parser.hs — Parser newtype with manually derived Functor, Applicative, Monad, and Alternative instances. Basic combinators (char, str, space, digit, etc.).

eopl/ — Essentials of Programming Languages (Friedman & Wand)

• eopl.scm — Exercises from the first two chapters in Racket's #lang eopl: recursive data structure manipulation, environment representations, binary tree operations, Church-encoded arithmetic (successor, predecessor, plus, times, factorial), and a stack implementation.

Textbooks

• Andrew Appel, Modern Compiler Implementation in ML (Ch. 1)
• Daniel Friedman & Mitchell Wand, Essentials of Programming Languages (Chs. 1–2)