A Rubyist's Road to Haskell

In this talk Cies Breijs shares his experiences in learning Haskell as his second language besides Ruby. He will do so from the point of view of a Rubyist: where possible comparing the two languages, available libraries/tools and their communities.

Transcript

1. A Rubyist’s Road to Haskell Cies Breijs Rotterdam Ruby Meetup @ ▲Hoppinger, 2015.01.19
2. Have you ever played the game “Set”?
3. Content 1. My road to Ruby 2. My road to Haskell 3. Ruby and Haskell compared 4. Why Haskell makes me happy? 5. Some code
4. My road to Ruby
5. Look at all the code I’m not writing!
6. My road to Haskell
7. My “next level” web lang short list Haskell (1990) So much to learn! Scala (2003) JVM, multi-paradigm was already showing its ugly face Clojure (2007) JVM, still dynamic typing (LISPish) Go (2009) Google owned (mixed blessing), merely a simple C, not FP
8. Language popularity...
9. Ruby and Haskell compared... ...remember “Set”?
10. Similarities Highlevelness Close to their paradigm Being "functional" as much as possible Mature library ecosystem
11. Differences Typing discipline Learning curve Creator: one pragmatic dev vs many scholars Attitude of community Interpreted vs compiled
12. Why Haskell makes me happy? Primarily: because bugs make me sad...
13. Bugs • Expensive • Demotivating (at least annoying) • Make refactoring costly • Mess with your estimates
14. Secondary reasons * Very fast (binaries are optimizable to C++ speed) * Pure-functional: no place to hide * Very innovative and knowledgeable community * I face the challenges up front * Haskell made me a better Rubyist (programmer) * Learned a lot of new, very useful, concepts * It’s a lot of fun!
15. Some code... main :: IO () main = putStrLn "Hello World!"
16. Some more code... addSqrs :: Int -> Int -> Int addSqrs x y = x^2 + y^2 -- Ruby: def add_sqrs(x, y); x**2 + y**2; end main = putStrLn $ "2^2 + 5^2 = " ++ addSqrs 2 5
17. Lists [] -- the empty list [1,2,3] -- List of Integrals ["foo","bar","baz"] -- List of Strings 1:[2,3] -- [1,2,3], (:) prepends one element 1:2:[] -- [1,2] [1,2] ++ [3,4] -- [1,2,3,4], (++) concatenates [1,2,3] ++ ["foo"] -- ERROR: expects only Integrals [1..] -- [1,2,3,4,5,6,7,8... ad infinitum
18. Types x :: Int -- x is of type Int y :: a -- y is of any type z :: Integral a => a -- z is of any "Integral type class"-type f :: a -> b -- f is a function from a to b g :: a -> b -> c -- g is a function from a to (b -> c) h :: (a -> b) -> [a] -> [b] -- h is a function from (a -> b) -- to ([a] -> [b])
19. More (from the IDE) main :: IO () main = do putStrLn "Hello World!" putStrLn $ show (take 7 squares) putStrLn $ show (take 7 fibs) putStrLn $ show (take 7 (mapAddSqrs [1..])) squares :: [Int] squares = map (^2) [1..] -- Ruby: nums.map{|i| i**2} fibs :: [Int] fibs = 0 : 1 : zipWith (+) fibs (tail fibs) addSqrs :: Int -> Int -> Int addSqrs x y = x^2 + y^2 mapAddSqrs :: [Int] -> [Int] mapAddSqrs = map (\i -> addSqrs i (i+1))
20. Haskell for the web • Yesod, Snap, Happstack. (Rails) • Scotty, Simple, Spock, Wheb, MFlow, and more. (Sinatra) • Haste, unifies client side (JS) and server side. • Other Haskell-to-JS compilers: GHCJS, Fay, PureScript. • All common web-technologies have one-or-more good libraries: Unicode, HTTP, URL, email, JSON, XML, HTML, CSS, SQL (Postgres, MySQL, Sqlite), Memcache, Redis, Mongo, etc.
21. Haskell at ▲Hoppinger LambdaCms
22. LambdaCms • Graduation project for two HRO C.S. students • Alpha version to be officially released in the following weeks • Sites compile to ~80MB binary (includes: server, all libs, all assets) • 27kB RES memory per thread • 2-10ms responses (involving SQL queries)
23. Wanna try? Bitemyapp’s “Learn Haskell” overview: https://github.com/bitemyapp/learnhaskell FPComplete’s School of Haskell https://www.fpcomplete.com/school FPComplete’s Haskell Center (web IDE) Just click on “Open in IDE” in School of Haskell...
24. Questions?