Data update

Task/Apply-a-callback-to-an-array/REXX/apply-a-callback-to-an-array.rexx

@@ -1,23 +1,52 @@
-/*REXX program applies a  callback  to an array  (using factorials for a demonstration).*/
-numeric digits 100                               /*be able to display some huge numbers.*/
-parse arg # .                                    /*obtain an optional value from the CL.*/
-a.=                                              /*initialize the array  A  to all nulls*/
-if #=='' | #==","  then #= 12                    /*Not assigned?  Then use default value*/
-                        do j=0  to #;   a.j= j   /*assign the integer   J  ───►   A.j   */
-                        end   /*j*/              /*array  A  will have N values: 0 ──► #*/
+-- 8 Sep 2025
+include Setting
 
-call listA   'before callback'                   /*display  A  array before the callback*/
-say                                              /*display a blank line for readability.*/
-say '      ··· applying callback to array A ···' /*display what is about to happen to B.*/
-say                                              /*display a blank line for readability.*/
-call bangit  'a'                                 /*factorialize (the values) of A array.*/
-                                                 /*    store the results  ───►  array B.*/
-call listA   ' after callback'                   /*display  A  array after the callback.*/
-exit 0                                           /*stick a fork in it,  we're all done. */
-/*──────────────────────────────────────────────────────────────────────────────────────*/
-bangit:   do v=0;  $= value(arg(1)'.'v);  if $=='' then return  /*No value?  Then return*/
-          call value arg(1)'.'v, fact($)         /*assign a value (a factorial) to array*/
-          end    /*i*/
-/*──────────────────────────────────────────────────────────────────────────────────────*/
-fact:   procedure; arg x;   != 1;         do f=2  to x;  != !*f;  end; /*f*/;     return !
-listA:    do k=0  while a.k\=='';  say arg(1)  'a.'k"="  a.k;     end  /*k*/;     return
+say 'APPLY A CALLBACK TO AN ARRAY'
+say version
+say
+call Task 'x'
+call Task ''
+call Task 'Sqrt(x)'
+call Task 'Sin(x)'
+call Task 'Exp(x)'
+exit
+
+Task:
+-- Get function to apply
+parse arg function
+-- Example array with x-values
+array.=0; n=10
+do i = 1 to n
+   array.i=i
+end
+array.0 = n
+if function = '' then do
+-- Apply fixed function to each element
+   do i = 1 to array.0
+      array.i=Square(array.i)
+   end
+   function='Square(x)'
+end
+else do
+-- Apply dynamic function to each element
+   do i = 1 to array.0
+      array.i=Std(Eval(function,array.i)/1)
+   end
+end
+-- Show after callback
+call Show
+return
+
+Show:
+say ' x' function
+do i = 1 to n
+   say Right(i,2) array.i
+end
+say
+return
+
+Square:
+arg xx
+return xx**2
+
+include Math