stdlib¶

Try¶

Try.map[B](f: A => B): transform successful values
Try.flatMap[B](f: A => Try[B]): tries to transform successful values
Try.recover[B](f: PartialFunction[Throwable, A]): Try[B]: transforms some failures to successes
Try.recover[B](f: PartialFunction[Throwable, Try[A]]): Try[B]: tries to transforms some failures to successes

map and flatMap evaluate after a future value is resolved
zip and traverse join together multiple Futures into a single Future and evaluated in parallel
recover and recoverWith handle failures

Use foldLeft to do computation based on an optional value
Use Either.fold(identity, identity) to return whichever of the Left or Right value is present, provided both are of the same type
When to use List, cats.data.Chain or Vector
BP Use List as default, IterableOnce as parameter and then call to get an Iterator
Iterable is a collection that can iterated multiple times by requesting a new Iterator using .iterate method
Iterator is a lightweight stateful object to iterate only once over an Iterable
- Iterator is discouraged in FP because it maintains a mutable state

intuition
applies to lists or sequences that can be thought as consisting of Cons and Nil
foldRight is constructor substitution, replacing Cons and Nil with different functions
is lazy, looking at each element as needed
works on infinite sequences
obeys associativity but the order isn't guaranteed, specifically, does not imply that it works from right to left
foldLeft is loop replacement
is strict, looping through all elements