To start with development, first we should be familiar with a few basic features of Haskell. We really need to know about laziness, datatypes, pattern matching, type classes, and basic notion of monads to start with Haskell.
Haskell is a language with lazy evaluation. From a programmer's point of view that means that the value is evaluated if and only if it is really needed. Imperative languages usually have a strict evaluation, that is, function arguments are evaluated before function application. To see the difference, let's take a look at a simple expression in Haskell:
let x = 2 + 3
In a strict or eager language, the
2 + 3 expression would be immediately evaluated to 5, whereas in Haskell, only a promise to do this ...