Oh category theory, bastion of strange and wonderful terminology, (some might say terrible and inaccessible). Love it or hate it, you're likely to run into some terms from category theory if you spend enough time in FP land. In this episode we'll tackle some of the terms that make up the 'ism family of terms, morphism, endomorphism, isomorphism, homomorphism, and catamorphism.

Denotational design talk: https://www.youtube.com/watch?v=bmKYiUOEo2A

8: Morphisms

Algebraic Data Types (ADTs) are one of the most distinguishing features of statically typed functional languages. Come learn why they exist, how you can use them, and how they change your design. 

Join the FP community at http://fpchat.com
Support us on Patreon at http://www.patreon.com/lambdacast
Follow us on Twitter: http://twitter.com/lambdacast

Show Notes:

Denotational Design with the example of a Poker game
https://fsharpforfunandprofit.com/ddd/

13: ADTs

The kind of type system a functional language uses has a large impact on the way you use that language. In this episode we discuss the tradeoffs involved in using a static or dynamic language.

Our patreon sponsors this month:

Javier Troconis
Andrew Newman
Derek Morr
Olov Johansson

Show Notes:

Philip Wadler Talk: https://www.infoq.com/presentations/category-theory-propositions-principle

Denotational Design 

Scott Wlaschin Poker Implementation
https://exit.sc/?url=https%3A%2F%2Ffsharpforfunandprofit.com%2Fddd%2F

Conal Elliot presentation on Denotational Design
https://www.youtube.com/watch?v=bmKYiUOEo2A

Our recomendation for a DDD book
https://www.amazon.com/Patterns-Principles-Practices-Domain-Driven-Design/dp/1118714709

14: Dynamic and Static Languages

Join us as we discuss the FP community. FP has a reputation as harsh and impenetrable but is that really the case? What can you do to make FP a more inviting place?

Episode 15 patrons:

Chris Lopes
Gabe Johnson
Randy Shepherd
Noel Waghorn

Correction: I incorrectly stated that one of the Recurse Center Social rules was “No Feigned Ignorance” it is actually “No Feigned Surprise”

Show Notes:

Cloud Haskell - http://haskell-distributed.github.io/tutorials/1ch.html

Recurse Center Social Rules - https://www.recurse.com/manual
Lambdaconf COC - http://fantasyland.institute/initiatives/COC.html
Moonconf COC - http://maitria.com/coc
Haskellbook - haskellbook.com
NY Haskell speaker guide - https://docs.google.com/document/d/1065iwf918SDotEPc0q9TWP_F1haVyeK90MSaBg3IOn8/edit

Spa day instead of pub meetup - https://twitter.com/sehurlburt/status/875848925529243648

Steven Syrek - https://twitter.com/sjsyrek

15: The FP Community

Going deeper down the category theory rabbit hole, we explore one of the most common and useful abstractions in the functional programming world. You're likely already familiar with Functors but just didn't know it yet.

Episode 16 patrons:
Chris Krycho
Tyler Harper
George Webster

Show Notes:

Functor
    map :: (a -> b) -> f a -> f b
Bifunctor
    bimap :: (a -> b) -> (c -> d) -> f a c -> f b d
Profunctor
    dimap :: (a -> b) -> (c -> d) -> f b c -> f a d

Phil Freeman's talk on Profunctors: https://www.youtube.com/watch?v=OJtGECfksds

16: Functors

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

18: Monads

Logan walks us through what his experience has been starting a JavaScript project in a functional style and using the best FP tools he can get in the JavaScript ecosystem.

Episode 19 patrons:
Nathan Sculli
Lee Beck
David Joyner
Nihohit
Charles Winebrinner

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

19: Starting A Project Functionally

Lazy evaluation is not normally something you hear programmers discussing but there is a lot of power available if you know how to use it. This episode we'll examine the differences between lazy and strict evaluation and look at use cases for laziness.

Episode 20 patrons:
Marcus Nielsen
Steven Loe
Ted Yavuzkurt
Michael Meyers
Szymon Beczkowski
Parl Naranja
Paul Brabban
Jason Sooter

Show Notes:
Memoization: https://codeburst.io/functional-memoization-in-javascript-adec62508bd0
Using IEnumerable in C# to generate an infinite sequence: https://brianreiter.org/2011/01/14/ienumerable-is-lazy-and-thats-cool/

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

20: Laziness

You may have seen generics in C#, Java, or Swift but there are a lot of very useful patterns using generics that rarely get used in an OO context. In this episode, we explore Type Parameters (aka generics) from a functional perspective and how using them can improve the structure of your applications.

Episode 21 patrons:
Scott Smith
Joel McCracken
Hakon Rossebo
Seth Utecht
Christophe Pereira da Conceicao
E. Mulder

Show Notes:
Add a type parameter video: https://www.youtube.com/watch?v=BHjIl81HgfE
Matt Parson's follow-up post: http://www.parsonsmatt.org/2017/04/08/maybe_use_a_type_parameter.html
Stephen’s Twitter: https://twitter.com/S11001001
Type Parameter example in Scala: https://typelevel.org/blog/2015/09/21/change-values.html

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

21: Type Parameters

This time we discuss the way data tends to be structured in functional languages and some of the similarities with databases and REST.

Episode 22 patrons:
Jason Sooter
Jamie Rolfs
Christian Hamburger
Daniel Svensson
Di Wen
Iulian Bojinca
Jonathan Fishbein
Nathan Sculli
Nels Wadycki
Paul Naranja
Peter Tillemans
Thomas Varney
Tyler Harper
weila wei
Dawn (שחר)


Show Notes:
CPPCast: http://cppcast.com/

John Soo - Sharing in Haskell
https://wiki.haskell.org/Sharing
https://stackoverflow.com/questions/1105765/generating-fibonacci-numbers-in-haskell

Alejandro’s link to Phantom Types article: https://www.objc.io/blog/2014/12/29/functional-snippet-13-phantom-types/

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

Intro/Outro music is "Lively Lumpsucker" by Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License

22: Structuring Data

LambdaCast is a podcast about functional programming for working developers. Our focus is to describe concepts using clear everyday language without watering anything down. If you've ever been curious about FP but were turned off by the jargon or unfamiliar concepts, this is the place to be.

Thoughts, comments, critique? Send them to contact@lambdacast.com

Music is "Lively Lumpsucker" by Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License

Icon is a modification of "Communicator" by Juan Pablo Bravo (https://thenounproject.com/term/communicator/47500/)
Licensed under Creative Commons: By Attribution 3.0 License