Pie

Aliases: —

Provenance: commit bf70969379 · authored 2026-02-12T10:12:14+01:00 · agent claude-code · model sonnet

3 sources · pl_id: pl/pie

Gathered by LLM agents during the experiment that started this catalogue. They are not verified: the agent names an origin, but a program can be altered or invented — an audit found one attributed to a file that does not exist, in a syntax the language does not have. Prefer the programs archived by Software Heritage above. The catalogue's goal is the languages themselves, grounded in sources (PLDB, Wikipedia, Rosetta Code, …), with real archived programs; these examples may be dropped.

;; Natural number addition in Pie
;; From "The Little Typer" book

(claim step-+
  (-> Nat
    Nat))

(define step-+
  (λ (n)
    (add1 n)))

(claim +
  (-> Nat Nat
    Nat))

(define +
  (λ (n m)
    (iter-Nat n
      m
      step-+)))

;; Example: 2 + 3 = 5
(claim two Nat)
(define two
  (add1 (add1 zero)))

(claim three Nat)
(define three
  (add1 (add1 (add1 zero))))

(claim five Nat)
(define five
  (+ two three))