Replace in Haskell

In Haskell, we can replace a substring within a string using the replace function from the Data.List library.

Here's the syntax for the replace function:

replace :: Eq a => [a] -> [a] -> [a] -> [a]

where the first argument is the substring to be replaced, the second argument is the replacement substring, and the third argument is the original string.

Here's an example to demonstrate the usage of the replace function:

import Data.List
main = do

  let originalString = "Hello, world!"

  let replacementString = "planet"

  let newString = replace "world" replacementString originalString

  putStrLn newString

In this example, the program replaces the substring "world" with the word "planet" in the original string "Hello, world!". The output is:

Hello, planet!

If the substring to be replaced is not found, the replace function does not modify the original string and returns the original string as it is.

Here's another example to demonstrate this case:

import Data.List
main = do

  let originalString = "This is a sample string."

  let replacementString = "example"

  let newString = replace "notfound" replacementString originalString

  putStrLn newString

In this example, the substring "notfound" is not found in the original string, so the replace function returns the original string as it is. The output is:

This is a sample string.