Data commit

Task/Ascending-primes/Dylan/ascending-primes.dylan

@@ -0,0 +1,37 @@
+define function prime? (n :: <integer>) => (p :: <boolean>)
+  case
+    n == 2
+      => #t;
+    n == 1 | remainder(n, 2) == 0
+      => #f;
+    otherwise
+      => let root = sqrt(as(<double-float>, n));
+         iterate loop (k = 3)
+           case
+             remainder(n, k) == 0 => #f;
+             k > root             => #t;
+             otherwise            => loop(k + 2);
+           end
+         end
+  end case
+end function;
+
+define function ascending-primes () => (primes :: <sequence>)
+  let maybe = make(<deque>);
+  for (k from 1 to 9)
+    push-last(maybe, k)
+  end;
+  let primes = make(<stretchy-vector>);
+  while (~empty?(maybe))
+    let n = pop(maybe);
+    if (prime?(n))
+      add!(primes, n)
+    end;
+    for (k from modulo(n, 10) + 1 to 9)
+      push-last(maybe, n * 10 + k)
+    end
+  end;
+  primes
+end function;
+
+format-out("%=", ascending-primes());