Ada ain't functional. A soft introduction is John English's Craft of Object-oriented programming. It's online, free, very intuitive and very well written. I usually tell folks to skip over the basics if they know them and work the first half. You're welcome to swing by #ada on Freenode for exceptionally friendly Ada talk. See what you think! I hope to see you on Freenode. :)
Secondly, I am unable to grok functional programming, which is why I quit trying to learn Haskell. I tried, I really tried but there's no way I'm able to wrap my head around functional programming. In my mind, there's a long list with two digits in hex, that the computer iterates as fast as possible. So if Ada is a functional only language that puts the brakes right there. If no, I'd be more than happy to start learning.