Associative array/Iteration: Difference between revisions
Content added Content deleted
(added ol) |
|||
| Line 1,967: | Line 1,967: | ||
(* in functional programming it is often more useful to fold over the elements *) |
(* in functional programming it is often more useful to fold over the elements *) |
||
CharMap.fold (fun k v acc -> acc ^ Printf.sprintf "key: %c - value: %d\n" k v) map "Elements:\n" ;;</lang> |
CharMap.fold (fun k v acc -> acc ^ Printf.sprintf "key: %c - value: %d\n" k v) map "Elements:\n" ;;</lang> |
||
=={{header|Ol}}== |
|||
<lang ol> |
|||
;;; create sample associative array |
|||
(define aa (list->ff '( |
|||
(hello . 1) |
|||
(world . 2) |
|||
(! . 3)))) |
|||
(print aa) |
|||
; ==> #((! . 3) (hello . 1) (world . 2)) |
|||
;;; simplest iteration over all associative array (using ff-iter, lazy iterator) |
|||
(let loop ((kv (ff-iter aa))) |
|||
(cond |
|||
((null? kv) #true) |
|||
((pair? kv) |
|||
(print (car kv)) |
|||
(loop (cdr kv))) |
|||
(else (loop (force kv))))) |
|||
; ==> (! . 3) |
|||
; ==> (hello . 1) |
|||
; ==> (world . 2) |
|||
;;; iteration with returning value (using ff-fold) |
|||
(print |
|||
"folding result: " |
|||
(ff-fold |
|||
(lambda (result key value) |
|||
(print "key: " key ", value: " value) |
|||
(+ result 1)) |
|||
0 |
|||
aa)) |
|||
; ==> key: !, value: 3 |
|||
; ==> key: hello, value: 1 |
|||
; ==> key: world, value: 2 |
|||
; ==> folding result: 3 |
|||
;;; same but right fold (using ff-foldr) |
|||
(print |
|||
"rfolding result: " |
|||
(ff-foldr |
|||
(lambda (result key value) |
|||
(print "key: " key ", value: " value) |
|||
(+ result 1)) |
|||
0 |
|||
aa)) |
|||
; ==> key: world, value: 2 |
|||
; ==> key: hello, value: 1 |
|||
; ==> key: !, value: 3 |
|||
; ==> rfolding result: 3 |
|||
;;; at least create new array from existing (let's multiply every value by value) |
|||
(define bb (ff-map aa |
|||
(lambda (key value) |
|||
(* value value)))) |
|||
(print bb) |
|||
; ==> #((! . 9) (hello . 1) (world . 4)) |
|||
</lang> |
|||
=={{header|ooRexx}}== |
=={{header|ooRexx}}== |
||