let map = \f lst. lst (\h sofar. make_list (f h) sofar) empty in
let filter = \f lst. lst (\h sofar. f h (make_list h sofar) sofar) empty in ; or
let filter = \f lst. lst (\h. f h (make_list h) I) empty in
+ let reverse = \lst. lst (\h t. t make_list (\f n. f h n)) empty in
; version 1 lists
; Rosenbloom's fixed point combinator
let Y = \f. (\h. f (h h)) (\h. f (h h)) in
; Turing's fixed point combinator
- let Z = (\u f. f (u u f)) (\u f. f (u u f)) in
+ let Theta = (\u f. f (u u f)) (\u f. f (u u f)) in
; length for version 1 lists
- fact Z 3 ; returns 6
+ fact Theta 3 ; returns 6
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