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Print type after evaluation +t,-t

With the +t option, the interpreter will display both the result and type of each expression entered at the Hugs prompt: 

 Prelude> :set +t

 Prelude> map (\x -> x*x) [1..10]

 [1, 4, 9, 16, 25, 36, 49, 64, 81, 100] :: [Int]

 Prelude> not True

 False :: Bool

 Prelude> \x -> x

 <> :: a -> a

 Prelude>
Note that the interpreter will not display the type of an expression if its evaluation is interrupted or fails with a run-time error. In addition, the interpreter will not print the type, IO (), of a program in the IO monad; the interpreter treats these as a special case, giving the programmer more control over the output that is produced.