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haskell: Phase 12 — Data.Set full API (union/intersection/difference/isSubsetOf/filter/map/foldr/foldl)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-07 11:39:11 +00:00

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;; set.sx — Phase 12 Data.Set: wraps Data.Map with unit values.
;;
;; A Set is a Map from key to (). All set operations delegate to the map
;; ops, ignoring the value side. Storage representation matches Data.Map:
;;
;; Empty → ("Map-Empty")
;; Node → ("Map-Node" key () left right size)
;;
;; Tradeoff: trivial maintenance burden, slight overhead per node from
;; the unused value slot. Faster path forward than re-implementing the
;; weight-balanced BST.
;;
;; Functions live in this file; the Haskell-level `import Data.Set` /
;; `import qualified Data.Set as Set` wiring (next Phase 12 box) binds
;; them under the chosen alias.
(define hk-set-unit (list "Tuple"))
(define hk-set-empty hk-map-empty)
(define hk-set-singleton (fn (k) (hk-map-singleton k hk-set-unit)))
(define hk-set-insert (fn (k s) (hk-map-insert k hk-set-unit s)))
(define hk-set-delete hk-map-delete)
(define hk-set-member hk-map-member)
(define hk-set-size hk-map-size)
(define hk-set-null hk-map-null)
(define hk-set-to-asc-list hk-map-keys)
(define hk-set-to-list hk-map-keys)
(define
hk-set-from-list
(fn (xs) (reduce (fn (acc k) (hk-set-insert k acc)) hk-set-empty xs)))
(define
hk-set-union
(fn (a b) (hk-map-union-with (fn (x y) hk-set-unit) a b)))
(define
hk-set-intersection
(fn (a b) (hk-map-intersection-with (fn (x y) hk-set-unit) a b)))
(define hk-set-difference hk-map-difference)
(define
hk-set-is-subset-of
(fn (a b) (= (hk-map-size (hk-map-difference a b)) 0)))
(define
hk-set-filter
(fn (p s) (hk-map-filter-with-key (fn (k v) (p k)) s)))
(define hk-set-map (fn (f s) (hk-set-from-list (map f (hk-map-keys s)))))
(define
hk-set-foldr
(fn (f z s) (hk-map-foldr-with-key (fn (k v acc) (f k acc)) z s)))
(define
hk-set-foldl
(fn (f z s) (hk-map-foldl-with-key (fn (acc k v) (f acc k)) z s)))