Haskell guards are used to test the properties of an expression; it might look like an if-else statement from a beginner’s view, but they function very differently. Haskell guards can be simpler and easier to read than pattern matching.
Let’s see an example
power :: Integer -> Integerpower x | x == 0 = 1 -- 1st guard| x /= 0 = x * x -- 2nd guardmain = doputStrLn "The square of 10 is:" -- Adding text for the outputprint (power 10) -- printing to screen
In the above coding example, we square the number:
In line 1: We instantiate our power function
In line 2: Our first guard, if x=0 let our `power’ be 1. (Just for illustration)
In line 3: Our second guard, multiplies the supplied number by itself (Squaring it)
In line 4: we initialize our main function
In line 5: we add a text for our output.
In line 6: We print our result
As stated earlier, guard can be seen as an if/else statement that is cleaner and easier to understand.
The square of 10 is: 100