Initial data commit

Task/Forward-difference/ALGOL-68/forward-difference.alg

@@ -0,0 +1,21 @@
+main:(
+  MODE LISTREAL = [1:0]REAL;
+
+  OP - = (LISTREAL a,b)LISTREAL: (
+    [UPB a]REAL out;
+    FOR i TO UPB out DO out[i]:=a[i]-b[i] OD;
+    out
+  );
+
+  FORMAT real fmt=$zzz-d.d$;
+  FORMAT repeat fmt = $n(UPB s-1)(f(real fmt)",")f(real fmt)$;
+  FORMAT list fmt = $"("f(UPB s=1|real fmt|repeat fmt)")"$;
+
+  FLEX [1:0] REAL s := (90, 47, 58, 29, 22, 32, 55, 5, 55, 73);
+
+  printf((list fmt,s,$";"l$));
+  TO UPB s-1 DO
+    s := s[2:] - s[:UPB s-1];
+    printf((list fmt,s,$";"l$))
+  OD
+)