Initial data commit

Task/Sort-three-variables/BCPL/sort-three-variables.bcpl

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+get "libhdr"
+
+// Sort 3 variables using a comparator.
+// X, Y and Z are pointers.
+let sort3(comp, x, y, z) be
+$(  sort2(comp, x, y)
+    sort2(comp, x, z)
+    sort2(comp, y, z)
+$)
+and sort2(comp, x, y) be
+    if comp(!x, !y) > 0
+    $(  let t = !x
+        !x := !y
+        !y := t
+    $)
+
+// Integer and string comparators
+let intcomp(x, y) = x - y
+let strcomp(x, y) = valof
+$(  for i=1 to min(x%0, y%0)
+        unless x%i = y%i
+            resultis intcomp(x%i, y%i)
+    resultis intcomp(x%0, y%0)
+$)
+and min(x, y) = x < y -> x, y
+
+// Run the function on both ints and strings
+let start() be
+$(  printAndSort(writen, intcomp, 7444, -12, 0)
+    printAndSort(writes, strcomp,
+        "lions, tigers, and",
+        "bears, oh my!",
+        "(from the *"Wizard of OZ*")")
+$)
+
+// Print the 3 values, sort them, and print them again
+and printAndSort(printfn, comp, x, y, z) be
+$(  print3(printfn, x, y, z) ; writes("*N")
+    sort3(comp, @x, @y, @z)
+    print3(printfn, x, y, z) ; writes("------*N")
+$)
+
+// Print 3 values given printing function
+and print3(printfn, x, y, z) be
+$(  writes("X = ") ; printfn(x) ; wrch('*N')
+    writes("Y = ") ; printfn(y) ; wrch('*N')
+    writes("Z = ") ; printfn(z) ; wrch('*N')
+$)