REPL

Start an interactive session of Haskell by running ghci.

A REPL (read-eval-print-loop) appears: the environment expects you to enter Haskell source code, which is read and evaluated to be able to print the result; all of this happens continuously in a loop.

We can enter the simple atomic expression 42, and the result is trivially going to be:

ghci> 42
42

We can try a slightly more complex expression, using the boolean literals​ True and False (note the first letter, which is capitalized) and the logic operators && (and) and || (or):

ghci> True && False
False

What is the result of evaluating the expression "P" ++ "S" ++ "25"?