In Haskell, the if/else expression works similarly to other programming languages. The syntax of the if/else statement is:
if condition then expression1 else expression2
Here, condition is the condition that is evaluated, and expression1 and expression2 are the results that are returned, depending on whether the condition is true or false.
Example:
Let's say we want to write a program that takes a number as input and checks whether it is even or odd. We can do this using the if/else statement as follows:
evenOdd :: Int -> String
evenOdd num = if (mod num 2 == 0) then "even" else "odd"
Here, evenOdd is a function that takes an integer value as input and returns either "even" or "odd" based on whether the input number is even or odd.
If the condition (mod num 2 == 0) is true, then the function returns "even", and if the condition is false, the function returns "odd".
We can call this function as follows:
evenOdd 2 -- returns "even"
evenOdd 3 -- returns "odd"
This is just one example of using the if/else statement in Haskell. There are many other ways to use it depending on the specific requirement of your program.