philnguyen / intern

Type-safe interning of datatypes in Typed Racket as subtype of Index

intern

Library for type-safe interning of a type as new subtype of Index in Typed Racket. This is useful when some (sub-)datatypes are carried around and compared for equality much more often than they are created (for example, the address component in AAM-style static analysis).

Install

raco pkg install intern

Example

The following example of interning a Setof String explicitly provides the default names to all optional arguments.

#lang typed/racket/base
(require racket/set intern)

(define-interner String-Set (Setof String)
  #:intern-function-name String-Set-of
  #:unintern-function-name of-String-Set)
;; Generates:
;;   String-Set-of : (Setof String) → String-Set
;;   of-String-Set : String-Set → (Setof String)
;;   count-String-Set : → Index

(define s₁ (String-Set-of (set "foo" "bar")))
(define s₂ (String-Set-of (set-add (of-String-Set s₁) "qux")))
(define s₃ (String-Set-of (set-add (of-String-Set s₂) "qux")))
(count-String-Set) ; ==> #t
(equal? s₂ s₃) ; ==> #t