Data commit

Task/Loops-Increment-loop-index-within-loop-body/Standard-ML/loops-increment-loop-index-within-loop-body.ml

@@ -0,0 +1,32 @@
+fun until done change dolast x =
+    if done x
+      then    dolast x
+      else    until done change dolast (change x);       (* iteration/generic loop *)
+
+
+val isprime = fn n :IntInf.int  =>
+let
+ fun butlast (_,t)   = t*t > n
+ fun divide (n,t)    = n mod t = 0 orelse t*t > n
+ fun trymore (n,t)   = (n,t + 2)
+in
+
+ n mod 2 <> 0 andalso until divide trymore butlast (n,3)
+
+end;
+
+val loop =  fn () =>
+let
+ fun butthislast (_,p,_) = rev p
+ fun wegot42 (n,_,_)     = n = 43
+ fun trymore (n,p,i)     = if isprime i
+                                   then ( n+1, (n,i)::p , i+i )
+                                   else ( n ,  p, i+1)
+in
+
+  until wegot42 trymore butthislast  (1,[],42)
+
+end ;
+
+val printp = fn clist:(int*IntInf.int) list =>
+ List.app (fn i=>print ((Int.toString (#1 i) )^" : "^ (IntInf.toString (#2 i) )^"\n")) clist ;