apl: ⍎ execute — eval string as APL source (+8)

- apl-execute: reassemble char-vector ravel into single string,
  then apl-run; handles plain string, scalar, and char-vector
- nested ⍎ ⍎ works; ⋄ separator threads through
- pipeline 148/148

lib/apl/tests/pipeline.sx

@@ -627,3 +627,37 @@
     "⊆ partition: outer length matches partition count"
     (len (get (apl-run "1 0 1 0 1 ⊆ ⍳5") :ravel))
     3))
+
+(begin
+  (apl-test
+    "⍎ execute: ⍎ '1 + 2' → 3"
+    (mkrv (apl-run "⍎ '1 + 2'"))
+    (list 3))
+  (apl-test
+    "⍎ execute: ⍎ '+/⍳10' → 55"
+    (mkrv (apl-run "⍎ '+/⍳10'"))
+    (list 55))
+  (apl-test
+    "⍎ execute: ⍎ '⌈/ 1 3 9 5 7' → 9"
+    (mkrv (apl-run "⍎ '⌈/ 1 3 9 5 7'"))
+    (list 9))
+  (apl-test
+    "⍎ execute: ⍎ '⍳5' → 1..5"
+    (mkrv (apl-run "⍎ '⍳5'"))
+    (list 1 2 3 4 5))
+  (apl-test
+    "⍎ execute: ⍎ '×/⍳5' → 120"
+    (mkrv (apl-run "⍎ '×/⍳5'"))
+    (list 120))
+  (apl-test
+    "⍎ execute: round-trip ⍎ ⎕FMT 42 → 42"
+    (mkrv (apl-run "⍎ ⎕FMT 42"))
+    (list 42))
+  (apl-test
+    "⍎ execute: nested ⍎ ⍎"
+    (mkrv (apl-run "⍎ '⍎ ''2 × 3'''"))
+    (list 6))
+  (apl-test
+    "⍎ execute: with assignment side-effect"
+    (mkrv (apl-run "⍎ 'q ← 99 ⋄ q + 1'"))
+    (list 100)))

lib/apl/transpile.sx

@@ -48,6 +48,7 @@
       ((= g "⎕←") apl-quad-print)
       ((= g "⍸") apl-where)
       ((= g "∪") apl-unique)
+      ((= g "⍎") apl-execute)
       (else (error "no monadic fn for glyph")))))
 
 (define
@@ -574,3 +575,11 @@
 (define apl-run (fn (src) (apl-eval-ast (parse-apl src) {})))
 
 (define apl-run-file (fn (path) (apl-run (file-read path))))
+
+(define
+  apl-execute
+  (fn
+    (arr)
+    (let
+      ((src (cond ((string? arr) arr) ((scalar? arr) (disclose arr)) (else (reduce str "" (get arr :ravel))))))
+      (apl-run src))))