Your wish is my IO ().
If I break, you can:
  1. Restart:           M-x haskell-process-restart
  2. Configure logging: C-h v haskell-process-log (useful for debugging)
  3. General config:    M-x customize-mode
  4. Hide these tips:   C-h v haskell-process-show-debug-tips
λ> fact 10
3628800
λ> fact 100
93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
λ> fact 100
0
λ> fact 10
3628800
λ> fact 15
1307674368000
λ> fact (-5)
*** Exception: /home/trifon/fmisync/Courses/2018_19/FPI_2018_19/sandbox/defs.hs:(4,1)-(6,32): Non-exhaustive patterns in function fact

λ> fact (-5)
*** Exception: Подадено отрицателно число!
CallStack (from HasCallStack):
  error, called at /home/trifon/fmisync/Courses/2018_19/FPI_2018_19/sandbox/defs.hs:7:17 in main:Defs
λ> let x = 2 in x + 3
5
λ> let x = 2
λ> x
2
λ> y = 3
λ> y
3
λ> fact (-5)
*** Exception: Подадено отрицателно число!
CallStack (from HasCallStack):
  error, called at /home/trifon/fmisync/Courses/2018_19/FPI_2018_19/sandbox/defs.hs:10:17 in main:Defs
λ> z
5
λ> fib (3-3)
0
λ> 2 □ 3
8
λ> 2 □ 3
8
λ> 2 □ 0
-4