Switch in Haskell

In Haskell, the switch statement is not available. However, the same functionality can be achieved using the case expression.

The case expression allows a value to be pattern matched against a series of patterns. When a pattern matches, the corresponding expression is evaluated and returned.

Here is an example of how to use case in Haskell:

isEven :: Int -> String
isEven n = case mod n 2 of
             0 -> "Even"
             1 -> "Odd"

In this example, we define a function isEven which take an Int argument and returns a String indicating whether the number is even or odd. We use the case expression to pattern match against the result of mod n 2, which gives us whether the number is even (0) or odd (1).

Another example:

getGrade :: Int -> String
getGrade score = case score of
                   90 -> "A"
                   80 -> "B"
                   70 -> "C"
                   _  -> "Fail"

In this example, we define a function getGrade which takes an Int argument and returns a String indicating the corresponding grade. We use the case expression to pattern match against the value of score. If the value of score is 90, 80, or 70, we return the corresponding grade ("A", "B", or "C"). If the value of score does not match any of the patterns, we return "Fail". The underscore symbol (_) is used as a catch-all pattern that matches any value.