public static final Option<Integer> parse(String) { try { return Option.<Integer>some(Integer.parseInt(String)); } catch(NumberFormatException ex) { return Option.<Integer>none(); } }

public static final F<String, Option<Integer>> parse = new F<String, Option>() { public Option<Integer> f(String text) { return parse(text); } }

Similar would be useful on the other number types.

How about ?

parseInt :: String -> Validation NumberFormatException Integer

readInt :: String -> Option Integer

Sure, sounds good to me. I've never used the Validation parts of FJ, but it sounds smart to use the name "parseInt" when you can get the Exception back like you would in "normal" Java.

Integers.fromString already exists as a first-class function.

There's also Validation.parseInt already.

Oh, I didn't see that in svn. Great!

Not implementing, since there are alternatives.