We use pattern matching in Haskell to simplify our codes by identifying specific types of expression. We can also use if-else as an alternative to pattern matching.
Pattern matching can also be seen as a kind of dynamic polymorphism where, based on the parameter list, different methods can be executed.
Check the following example to see how to carry out a simple pattern match.
sq :: Int -> Intsq 0 = 1 --first patternsq n = n * n -- second patternmain = doputStrLn "The square of 5 is:" -- adding text decsriptionprint (sq 5) --calling the sq function and printing output
In the example above:
In line 1, we enter the sq function, which squares a number.
In line 2, we create our first pattern to match for zero.
In line 3, we create our second pattern to square any other supplied value besides 0.
In line 6, we add a text description for our output.
In line 7, we call the sq function and print the output.