What even is a cat? (WIP)
Agenda
- Motivation
- Recap: FP without effects
- Examples of effects
- How to compose effects
Motivation
I saw something like "F[_]: Applicative" in the code.
Do we use this anywhere else already?
Short answer: Yes, in many places
Longer answer: ...this talk
Recap: FP
"Functional Programming is writing programs with (pure) functions and (immutable) data"
~ Me ;)
Functions
Data
+
Focus of this talk
Recap: FP
If a function...
- ...is defined for every possible input, it is called total
- ...only uses its input to calculate its output and does nothing else, it is called pure (= no side-effects)
=> The ideal is to make all functions total and pure
Recap: Function composition
In reality...
-
Partiality (Option)
-
Errors (Either)
-
Nondeterminism (List)
- Concurrency (Future)
- ...and many more
A => Option[B]
A => Either[?, B]
A => List[B]
A => Future[B]
The Foundation
Functor
Applicative
Monad
map
ap
pure
flatMap
pure
(flatten)
(product, zip, mapN)
"Transform values inside an effect"
"Compose effects independently"
"Compose effects dependently"
Let's try an example
Inspirations for this talk
-
"Functional Programming with Effects" ~ Rob Norris
-
"Applicative: The Origin Story" ~ Justin Heyes-Jones
What even is a cat? (WIP)
By Felix Bruckmeier
What even is a cat? (WIP)
FP with effects in Scala (using cats)
