Implementations of several variants of the lambda calculus in OCaml. For each variant, an interpreter and a compiler to JavaScript are provided. Currently, there are four variants:

• untyped: Almost pure, untyped lambda calculus, with integers, a print statement, and let-in added in order to give the language a semblance of usability. The file untyped/test/ackermann.lam contains implementations of several sorting algorithms in this language.
• simplytyped: Simply typed lambda calculus, with a fix operator added in order to enable recursion. I also added if statements and boolean variables.
• typeinference: Like the previous implementation, but without the need to make every type explicit. The implementation uses constraint-based typing and the Hindley-Milner algorithm. This variant also supports pairs, the unit type, sum types, algebraic data types, pattern matching, records, let-polymorphism, and higher-order types.
• subtyping: A fork of the typeinference variant with rudimentary support for subtyping on records. I wrote these programs primarily to learn, not to provide a useful programming language.