set.lambda: Move set operations there.

Author: aartaka

README.org

@@ -26,6 +26,7 @@ Sources of inspiration and code:
   - ~numbers.lambda~ :: Numeric, arithmetics. Depends on ~combinators.lambda~ and ~bool.lambda~.
   - ~cons.lambda~ :: Conses. Depends on ~bool.lambda~.
   - ~list.lambda~ :: Linked lists and utils for them. Mostly fold operations. Depends on ~cons.lambda~, ~numbers.lambda~, ~combinators.lambda~, ~bool.lambda~.
+    - ~set.lambda~ :: Operations on lists-as-sets. Depends on ~list.lambda~ and its transitive dependencies.
   - ~alist.lambda~ :: Associative (key-value) lists. Depends on ~cons.lambda~ and ~combinators.lambda~.
   - ~alias.lambda~ :: Aliases for all of the above.
 - Run the code using these primitives. Say

list.lambda

@@ -21,10 +21,6 @@ rotatel = λl.rcons (cdr l) (car l)
 rotater = λl.cons (last l) (butlast l)
 take = λn.λl.Y (λr.λl.if (eq n (length l)) l (r (butlast l))) l
 split = λn.λl.(cons (take n l) (singleton (nthcdr n l)))
-deduplicate = λp.λl.foldr (λe.λa.if (some (λx.p x e) a) a (cons e a)) nil l
-difference = λp.λa.λb.remove (λe.(some (λx.p x e) b)) a
-intersection = λp.λa.λb.filter (λe.(some (λx.p x e) b)) a
-union = λp.λa.λb.deduplicate p (concat a b)
 unzip = λl.(cons (map car l) (singleton (map cadr l)))
 
 sorted = λl.foldr (λe.λa.(cons (and (car a) (leq e (cdr a))) e)) (cons true (last l)) (butlast l)

set.lambda

@@ -0,0 +1,4 @@
+deduplicate = λp.λl.foldr (λe.λa.if (some (λx.p x e) a) a (cons e a)) nil l
+difference = λp.λa.λb.remove (λe.(some (λx.p x e) b)) a
+intersection = λp.λa.λb.filter (λe.(some (λx.p x e) b)) a
+union = λp.λa.λb.deduplicate p (concat a b)