September Morn Update

Task/Mutual-recursion/ABAP/mutual-recursion.abap

@@ -0,0 +1,47 @@
+report z_mutual_recursion.
+
+class hoffstadter_sequences definition.
+  public section.
+    class-methods:
+      f
+        importing
+          n             type int4
+        returning
+          value(result) type int4,
+
+      m
+        importing
+          n             type int4
+        returning
+          value(result) type int4.
+endclass.
+
+
+class hoffstadter_sequences implementation.
+  method f.
+    result = cond int4(
+      when n eq 0
+      then 1
+      else n - m( f( n - 1 ) ) ).
+  endmethod.
+
+
+  method m.
+    result = cond int4(
+      when n eq 0
+      then 0
+      else n - f( m( n - 1 ) ) ).
+  endmethod.
+endclass.
+
+
+start-of-selection.
+  write: |{ reduce string(
+    init results = |f(0 - 19): { hoffstadter_sequences=>f( 0 ) }|
+    for i = 1 while i < 20
+    next results = |{ results }, { hoffstadter_sequences=>f( i ) }| ) }|, /.
+
+  write: |{ reduce string(
+    init results = |m(0 - 19): { hoffstadter_sequences=>m( 0 ) }|
+    for i = 1 while i < 20
+    next results = |{ results }, { hoffstadter_sequences=>m( i ) }| ) }|, /.

Task/Mutual-recursion/BASIC/mutual-recursion-2.basic

@@ -0,0 +1,16 @@
+      @% = 3 : REM Column width
+      PRINT "F sequence:"
+      FOR i% = 0 TO 20
+        PRINT FNf(i%) ;
+      NEXT
+      PRINT
+      PRINT "M sequence:"
+      FOR i% = 0 TO 20
+        PRINT FNm(i%) ;
+      NEXT
+      PRINT
+      END
+
+      DEF FNf(n%) IF n% = 0 THEN = 1 ELSE = n% - FNm(FNf(n% - 1))
+
+      DEF FNm(n%) IF n% = 0 THEN = 0 ELSE = n% - FNf(FNm(n% - 1))

Task/Mutual-recursion/BASIC/mutual-recursion-3.basic

@@ -0,0 +1,23 @@
+100 PROGRAM "Hofstad.bas"
+110 PRINT "F sequence:"
+120 FOR I=0 TO 20
+130   PRINT F(I);
+140 NEXT
+150 PRINT :PRINT "M sequence:"
+160 FOR I=0 TO 20
+170   PRINT M(I);
+180 NEXT
+190 DEF F(N)
+200   IF N=0 THEN
+210     LET F=1
+220   ELSE
+230     LET F=N-M(F(N-1))
+240   END IF
+250 END DEF
+260 DEF M(N)
+270   IF N=0 THEN
+280     LET M=0
+290   ELSE
+300     LET M=N-F(M(N-1))
+310   END IF
+320 END DEF

Task/Mutual-recursion/Elena/mutual-recursion.elena

@@ -1,20 +1,20 @@
-import extensions.
-import system'collections.
+import extensions;
+import system'collections;
 
-F = (:n)((n == 0) ifTrue:[^1] ifFalse:[ ^n - (M(F(n-1))) ] ).
-M = (:n)((n == 0) ifTrue:[^0] ifFalse:[ ^n - (F(M(n-1))) ] ).
+F = (n => (n == 0) ? 1 : (n - M(F(n-1))) );
+M = (n => (n == 0) ? 0 : (n - F(M(n-1))) );
 
-program =
-[
-    var ra := ArrayList new.
-    var rb := ArrayList new.
+public program()
+{
+    var ra := new ArrayList();
+    var rb := new ArrayList();
 
-    0 to:19 do(:i)
-    [
-        ra append(F eval:i).
-        rb append(M eval:i).
-    ].
+    for(int i := 0, i <= 19, i += 1)
+    {
+        ra.append(F(i));
+        rb.append(M(i))
+    };
 
-    console printLine(ra).
-    console printLine(rb).
-].
+    console.printLine(ra.asEnumerable());
+    console.printLine(rb.asEnumerable())
+}

Task/Mutual-recursion/Ol/mutual-recursion.ol

@@ -0,0 +1,8 @@
+(letrec ((F (lambda (n)
+               (if (= n 0) 1
+                  (- n (M (F (- n 1)))))))
+         (M (lambda (n)
+               (if (= n 0) 0
+                  (- n (F (M (- n 1))))))))
+   (print (F 19)))
+; produces 12

Task/Mutual-recursion/Phix/mutual-recursion.phix

@@ -0,0 +1,17 @@
+forward function M(integer n)
+
+function F(integer n)
+    return iff(n?n-M(F(n-1)):1)
+end function
+
+function M(integer n)
+    return iff(n?n-F(M(n-1)):0)
+end function
+
+for i=0 to 20 do
+    printf(1," %d",F(i))
+end for
+printf(1,"\n")
+for i=0 to 20 do
+    printf(1," %d",M(i))
+end for

Task/Mutual-recursion/VBA/mutual-recursion.vba

@@ -0,0 +1,26 @@
+Private Function F(ByVal n As Integer) As Integer
+    If n = 0 Then
+        F = 1
+    Else
+        F = n - M(F(n - 1))
+    End If
+End Function
+
+Private Function M(ByVal n As Integer) As Integer
+    If n = 0 Then
+        M = 0
+    Else
+        M = n - F(M(n - 1))
+    End If
+End Function
+
+Public Sub MR()
+    Dim i As Integer
+    For i = 0 To 20
+        Debug.Print F(i);
+    Next i
+    Debug.Print
+    For i = 0 To 20
+        Debug.Print M(i);
+    Next i
+End Sub