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Haskell Program to Print 8-Star Pattern
In this tutorial, we are going to learn how to develop a Haskell program to print 8 start patterns using the internal replicate and concat function.
An '8' star pattern is an ASCII art representation of the number 8 using asterisks. as shown below −
******** * * * * ******** * * * * ********
The asterisks are arranged in such a way that they form the shape of the number 8.
Algorithm
Step 1 − The printLine function is defined using replicate function as,
Step 2 − Program execution will be started from main function. The main() function has whole control of the program. It is written as main = do. In the main function, a number is passed up to which the 8 star pattern is to be printed.
Step 3 − The variable named, “n” is being initialized. It will hold the integer up to which the 8 star pattern is to be printed.
Step 4 − The result is printed to the console using ‘putStrLn’ statement after the function is called.
In this method, an ASCII art representation of the number 8 is printed. The printEight function takes an integer n as an argument and returns a string that represents the number 8. The printLine function takes an integer n as an argument and returns a string of n asterisks followed by a newline character.
Example 1
In this example, the function is defined using the replicate function to print the 8 star pattern.
module Main where printLine :: Int -> String printLine n = replicate n '*' ++ "
" printEight :: Int -> String printEight n = concat [ printLine n , "*" ++ replicate (n-2) ' ' ++ "*
" , printLine n , "*" ++ replicate (n-2) ' ' ++ "*
" , printLine n ] main :: IO () main = putStr (printEight 8)
Output
******** * * ******** * * ********
Example 2
In this example, the function is defined using the replicate function to print the 8 star pattern.
module Main where printRow :: Int -> String printRow n = replicate n '*' ++ "
" printEight :: Int -> String printEight n = concat [ printRow n , "*" ++ replicate (n-2) ' ' ++ "*
" , "*" ++ replicate (n-2) ' ' ++ "*
" , printRow n , "*" ++ replicate (n-2) ' ' ++ "*
" , "*" ++ replicate (n-2) ' ' ++ "*
" , printRow n ] main :: IO () main = putStr (printEight 8)
Output
******** * * * * ******** * * * * ********
Conclusion
In this article we learned how to creat a haskell program that will pring a 8 start pattern using internal functions like replicate and concat function
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