README

Rustpie is a Rust implementation of the Pie, a dependently typed language with a Lisp-like syntax. The language is formally specified in the book The Little Typer.

Rustpie is currently in very early development.

Diffrences from the canonial Pie implementation

There are some differences between the Pie language in Rustpie and the canonical Pie implementation.

REPL & file descrepency

(exit)

Rustpie adds the command (exit) to exit the REPL. It can only be used in the repl and cannot be used in source files.

Definitions in REPL

In the canonical implementation, you must claim and define in a file. Rustpie does not have this restriction, and you can add definitions directly in the REPL.

cons

In the canonical implementation, constructing pairs using cons directly in the REPL results in the “Can’t determine a type” error. Rustpie repl does not have this restriction, and it will happily infer the type:

>>> (cons 1 'a)
(the (Pair Nat Atom) (cons 1 'a))