chrysanthemum is a simple language with a complex type system, initially written as a term project for CPSC 539. It implements a number of features from the excellent Types and Programming Languages, including:

• The simply typed lambda calculus
• Bidirectional type checking and subtyping support
• A somewhat complex type system: including support for:
  • unit, bool, int, nat, float, str,
  • struct, tuple, union, list, array, slice,
  • interface, empty, error

• the simple lambda calculus: implement execute
• to be fancy: implement parse
• to lose my sanity: implement parse_file
• bidirectional typechecking: implement infer and check
• extend to additional basic types: refactor Term
• extend to complex types: improve subtype
• meet my original standards: implement interface
• make complex types useful: implement access
• type classes: implement monomorphize
• simple effects: extend ast
• testtesttest

src/
src/main.rs    # the user facing program
src/simple.rs  # the simple lambda calculus: execution
src/ast.rs     # the fundamental representation of types and terms
src/bidirectional.rs # the core of the language: checking, inference
src/unification.rs   # an alternate core: checking and inference by unification
src/parser.rs        # parses user programs into proper data structures
src/monomorphize.rs  # a monomorphization pass for type classes
src/effects.rs       # code for effects idk
test/ # various tests

• Types and Programming Languages
• Advanced Topics in Types and Programming Languages
• Bidirectional Typing Rules: A Tutorial
• Bidirectional Typechecking
• Bidirectional Type Class Instances
• Typechecking for Higher-Rank Polymorphism
• How to make ad-hoc polymorphism less ad-hoc