This is a demo of the prototype MLsub type inference engine, which does Hindley-Milner style type inference with subtyping. Edit the code on the left, and its type will be printed on the right.
The syntax is a fragment of OCaml, with functions, let, lists, and records.
The MLsub typechecker is written in OCaml, and the code is available on github.
A preprint paper about MLsub is available. More details are available in my thesis (draft manuscript here).