Supertype is an extension of lean's Subtype that provides addional conveniences, features and syntax.

To get started, add the following line to your lakefile.lean.

require supertype from git "https://github.com/somombo/supertype" @ "main"

At the top of every lean file where you want to use Supertypes, add:

import Supertype

Then you can use the package in the following manner:

def x : { // 5 + · < 17 } := 2 ...
def y : { (a, b) // 5 ≤ a + b } := ... (4,3)

(For more examples of usage and syntax, See Examples.lean file)