programing

Building on the power of functors we examine a few scenarios where a normal Functor is problematic. Fortunately, there is a closely related structure known as an Applicative Functor that can provide the capabilities to solve a broader range of problems.

Episode 17 patrons:

Chad Wooley
David Keathley
Andre Carvalho

Show Notes:

Coconut programming language: http://coconut-lang.org/

Hack nights instead of presentations: http://tech.noredink.com/post/142283641812/designing-meetups-to-build-better-communities

class Functor f => Applicative f where
  pure :: Applicative f => a -> f a
  ap :: Applicative f => f (a -> b) -> f a -> f b

Example of applicative usage:

pure (+) <*> Just 3 <*> Just 2 -- this results in Just 5
(+) <$> Just 3 <*> Just 2 -- this is the same as above
liftA2 (+) (Just 3) (Just 2) -- alternate form using lift instead of infix operators

17: Applicative Functors

Monads, the promised land of functional programming. Or at least with all the hype they'd better be! Come join the cast as we demystify this overhyped structure that has become an indispensable part of many functional programmer's toolkits.

Episode 18 patrons:
Pluton
Tim Buckley
Huge shout out to Marcus Nielsen

Show Notes:
bind :: m a -> (a -> m b) -> m b

Example of do syntax vs using bind aka >>=:
main = do
foo <- doMonadyThing
foo2 <- doOtherMonadyThing foo
pure (whatever foo foo2)

main = doMonadyThing
>>= (\foo -> doOtherMonadyThing foo 
>>= (\foo2 -> pure (whatever foo foo2))
)

Extracting a value from a Maybe

extract :: Just Int -> Int
extract foo = case foo of
Just num -> num
Nothing -> 0

Railroad oriented programming talk by Scott Wlaschin
fsharpforfunandprofit.com/rop/

FP Chat Slack Community: https://fpchat-invite.herokuapp.com

programing

GreenTea