Haskell Cookbook

How it works...

• The error function takes a string, and creates an exception. However, this exception is realizable only in the IO monad. Hence, we catch it while we are printing the result of div1.
• The function catch runs an IO action and takes a handler to catch the exception. It is possible to catch all exceptions by specifying the type of exception as SomeException. 
• The try function also runs an IO action. However, it returns the result in Either e a where e is the exception and a is the result of the IO action. Thus, we can check using Either that we have a valid result. 
• Typically, IO functions such as readFile raise an exception of type IOException. 
• We can create custom exceptions by creating an instance of Show and Exception. The ...