on 05-Jul-2020 (Sun)

Inside function myAdd :: a -> a -> a
you’d need the ability to manually check that you were adding only the types it makes sense to add
(which isn’t possible in Haskell).

If you add deriving Ord to your definition of Icecream , Haskell defaults to the order of the data constructors for determining Ord .

GHCi> [S1 .. ] [one,two,three,four,five,six,*** Exception: No such value
Yikes!
You get an error because you didn’t handle the case of having a missing value.
But if you had just derived your type class, this wouldn’t be a problem

Each of the downstream nations relies on access to the freshwater flowing out from Ethiopia, and this grants Addis Ababa political leverage across East Africa

Addis Abba did not possess the means to shape nature.

The primary method of power generation in Ethiopia is hydroelectricity.

The biggest hydroelectic dam in Africa is the Grand Ethiopian Renaissance Dam and its power stations along the Blue Nile River.

Ever since the loss of its coastal territory in Eritrea, Ethiopia has been stripped of its access to the sea

Today, Ethiopia relies on neighbouring Djibouti for 95 per cent of its trade.

Types in Haskell allow you to view programs as a series of transformations.

You can think of transformations as a more abstract level of thinking about functions. When solving problems in Haskell, you can approach them first as a sequence of abstract transformations.

mconcat = foldr mappend mempty

Note that the reason mconcat uses foldr instead of foldl is due to the way that foldr can work with infinite lists, whereas foldl will force the evaluation.