June 2018 Update

Task/Perfect-numbers/Julia/perfect-numbers.julia

@@ -1,3 +1,4 @@
-function isperfect(n)
-  n == sum([n % i == 0 ? i : 0 for i = 1:n-1])
-end
+isperfect(n::Integer) = n == sum([n % i == 0 ? i : 0 for i = 1:(n - 1)])
+perfects(n::Integer) = filter(isperfect, 1:n)
+
+@show perfects(10000)

Task/Perfect-numbers/Modula-2/perfect-numbers.mod2

@@ -0,0 +1,43 @@
+MODULE PerfectNumbers;
+
+FROM SWholeIO IMPORT
+  WriteCard;
+FROM STextIO IMPORT
+  WriteLn;
+FROM RealMath IMPORT
+  sqrt;
+
+VAR
+  N: CARDINAL;
+
+PROCEDURE IsPerfect(N: CARDINAL): BOOLEAN;
+VAR
+  S, I: CARDINAL;
+  SqrtN: REAL;
+BEGIN
+  S := 1;
+  SqrtN := sqrt(FLOAT(N));
+  IF N REM 2 = 0 THEN
+    S := S + 2 + N / 2;
+  END;
+  I := 3;
+  WHILE FLOAT(I) <= SqrtN - 1.0 DO
+    IF N REM I = 0 THEN
+      S := S + I + N / I;
+    END;
+    I := I + 1;
+  END;
+  IF I * I = N THEN
+    S := S + I;
+  END;
+  RETURN (N = S);
+END IsPerfect;
+
+BEGIN
+  FOR N := 2 TO 10000 BY 2 DO
+    IF IsPerfect(N) THEN
+      WriteCard(N, 5);
+      WriteLn;
+    END;
+  END;
+END PerfectNumbers.

Task/Perfect-numbers/Perl-6/perfect-numbers.pl6

@@ -1 +1,4 @@
-sub perf($n) { $n == [+] grep $n %% *, 1 .. $n div 2 }
+sub is-perf($n) { $n == [+] grep $n %% *, 1 .. $n div 2 }
+
+# used as
+put (grep {.&is-perf}, 1..Inf)[^4];