apl: ⊥ decode / ⊤ encode (mixed-radix; +11)

- apl-decode: Horner reduce; scalar base broadcasts to digit length
- apl-encode: right-to-left modulo + floor-div
- 24 60 60 ⊥ 2 3 4 → 7384, 24 60 60 ⊤ 7384 → 2 3 4
- pipeline 132/132

lib/apl/runtime.sx

@@ -886,6 +886,33 @@
         (b-ravel (if (scalar? b) (list (disclose b)) (get b :ravel))))
       (apl-vector (filter (fn (x) (index-of b-ravel x)) a-ravel)))))
 
+(define
+  apl-decode
+  (fn
+    (base digits)
+    (let
+      ((d-ravel (if (scalar? digits) (list (disclose digits)) (get digits :ravel))))
+      (let
+        ((d-len (len d-ravel)))
+        (let
+          ((b-ravel (if (scalar? base) (let ((b (disclose base))) (map (fn (i) b) (range 0 d-len))) (get base :ravel))))
+          (let
+            ((result (reduce (fn (acc i) (if (= i 0) (nth d-ravel 0) (+ (* acc (nth b-ravel i)) (nth d-ravel i)))) 0 (range 0 d-len))))
+            (apl-scalar result)))))))
+
+(define
+  apl-encode
+  (fn
+    (base val)
+    (let
+      ((b-ravel (if (scalar? base) (list (disclose base)) (get base :ravel)))
+        (n (if (scalar? val) (disclose val) (first (get val :ravel)))))
+      (let
+        ((b-len (len b-ravel)))
+        (let
+          ((result (reduce (fn (acc-and-n i) (let ((acc (first acc-and-n)) (rem (nth acc-and-n 1))) (let ((b (nth b-ravel (- (- b-len 1) i)))) (if (= b 0) (list (cons rem acc) 0) (list (cons (modulo rem b) acc) (floor (/ rem b))))))) (list (list) n) (range 0 b-len))))
+          (apl-vector (first result)))))))
+
 (define
   apl-primes
   (fn