on 04-Jul-2020 (Sat)

Both performance and computational differences exist between foldl and foldr . At this stage in learning, it’s important to know that these functions give different answers if the order of the application matters

foldl is the most intuitive behaving of the folds, but it usually has terrible performance and can’t be used on infinite lists.
foldl' is a nonlazy version of foldl that’s often much more efficient.
foldr is often more efficient than foldl and is the only fold that works on infinite lists

Many recursive problems can be solved with map , filter , and foldl . When encountering a recursive problem, the first question you should ask is whether you can solve it with one of these three functions.

Prototype-based object-oriented languages, such as JavaScript, create instances of objects by modifying a prototypical object, rather than using classes. Prototypes in Java- Script are often a source of much confusion. Here you can see how cloning an object and modifying it to create a new object is a natural result of using functional programming. In Haskell, you can create new objects by modifying copies of old, existing ones

Used closures to represent objects created with lambda functions

Sent messages to objects by using first-class functions

Managed state in a functional way, allowing you to be more exact in controlling program execution

Types in Haskell are more abstract. They provide a way of understanding how values behave and how to organize data.

in Haskell literal numbers are polymorphic: their type is determined from the compiler based on the way they’re used.

what should Haskell do here?

z = read "6"

Just as with regular variables, using different names for type variables doesn’t imply that the values represented by the variables must be different, only that they can be.

When you have two names for the same type, it’s referred to as a type synonym. Type synonyms are extremely useful, because they make reading type signatures much easier.