Functional Brighton Meet up: what functional programming means to me.

Transcript

1. Three things I’ve noticed about functional programming while using Scala.

2. happy birthday to me happy birthday to me #lol #omg

   oops #lol oops #lol #omg 㱺 㱺 ⋮ ⋮ What have we have? What do we want?

3. #lol, #omg & some text Some text 㱺 What have

   we have? What do we want?

4. #lol, #omg & some text Some text 㱺 What have

   we have? What do we want? List[String], String 㱺 String

5. def appendTags(tweet: String, tags: List[String]) = tags.foldLeft(tweet) { appendOne }

   def appendOne(tweet: String, tag: String) = if (tweet contains tag) tweet else tweet+" "+tag

6. “It’s the mutable state, stupid.” – Göetz et al.

7. val results = List(yahoo _, google _).par.map(_.apply)

8. import scala.actors.Futures._ val results = List(yahoo _, google _) map

   ( f 㱺 future{ f() } ) map (_.apply)

9. Option, for comprehensions, flatMap & pattern matching are astonishingly useful

   every day and I’d never heard of them before learning Scala.

10. for (int i = 0; i < resultFeed.getEntries().size(); i++) {

    ContactEntry entry = resultFeed.getEntries().get(i); if (entry.hasName()) { Name name = entry.getName(); if (name.hasFullName()) { ...

11. for { entry ← resultFeed.getEntries name ← Option(entry.getName) full_name ←

    Option(name.getFullName) birthday ← Option(entry.getBirthday) } yield "%s: %s".format(full_name.getValue, when)

12. 1. Thinking in terms of A 㱺 B 2. Concurrency

    3. Option (& friends) change everything Summary

13. StringBuffer b = new StringBuffer(tweet); if (tags != null) {

    for(String tag: tags) { if (tag != null && b.indexOf(tag) == -1) { b.append(tag).append(“ ”); } } } return b.toString();