let x = 2;
    y = 3; in
  (x y)

let x: (Int) =
      let y: (Int) = { x }; in
        y;
    y: (Int) = 3;
    f: (((Int) -> (Int)) -> Int) = [a, b] { ((plus a) b) }; in
  ((f x) y)
---


LetStatement: "let" [Assignment ";"]+ "in" Body
Binding: Ident (":" TypeDecl)?
Assignment: Binding "=" Statement
Statement: LetStatement | Abstraction
Computation: Identifier | Application | Abstraction
Application: "(" Computation Computation ")"
Abstraction: "[" UncurriedArguments "]" "{" Computation "}"

LetStatement: "let" Ident (":" TypeDecl)? "=" Computation in

BaseType: Identifier
Arrow: TypeDecl "->" TypeDecl
TypeDecl: "(" BaseType | Arrow ")"

Binding: Identifier (":" TypeDecl)?
UncurriedArguments: Identifier ["," Identifier]+
Abstraction: UncurriedArguments "{" Binding "=>" Computation "}"