The next big Haskell project is about to start!
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
Changed directory: /home/trifon/fmisync/Courses/2019_20/FP_2019_20/sandbox/lectures/haskell/
λ> 2
2
λ> :t (^)
(^) :: (Integral b, Num a) => a -> b -> a
λ> :t (^^)
(^^) :: (Fractional a, Integral b) => a -> b -> a
λ> :t (**)
(**) :: Floating a => a -> a -> a
λ> div50 2
25
λ> div50 12
4
λ> :t twice
twice :: (t -> t) -> t -> t
λ> :t f
f :: Num p1 => p2 -> p3 -> p4 -> p5 -> p1
λ> :t (f 5 8)
(f 5 8) :: Num p1 => p4 -> p5 -> p1
λ> :t (f 5 8) 2 3
(f 5 8) 2 3 :: Num p1 => p1
λ> :t diag
diag :: (t1 -> t1 -> t2) -> t1 -> t2
λ> hypothenuse `diag` 1
1.4142135623730951
λ> :t (1+)
(1+) :: Num a => a -> a
λ> :t (+) 1
(+) 1 :: Num a => a -> a
λ> subtract 5 8
3
λ> (subtract 5) 8
3
λ> lastDigit 123
10
λ> lastDigit 123
3
λ> fact (-1)
*** Exception: /home/trifon/fmisync/Courses/2019_20/FP_2019_20/sandbox/lectures/haskell/Defs.hs:(3,1)-(5,29): Non-exhaustive patterns in function fact

λ> :t error
error :: [Char] -> a
λ> fact (-1)
*** Exception: Отрицателен аргумент!
CallStack (from HasCallStack):
  error, called at /home/trifon/fmisync/Courses/2019_20/FP_2019_20/sandbox/lectures/haskell/Defs.hs:6:14 in main:Defs
λ> let x = 2
λ> x
2
λ> let x = 5
λ> x
5
λ> x = 10
λ> x
10
λ> x = 12
λ> x = 15
λ> area 0 0 (-3) 0 0 4
6.0
Defs.hs:20:1: error: …
    Multiple declarations of ‘x’
    Declared at: /home/trifon/fmisync/Courses/2019_20/FP_2019_20/sandbox/lectures/haskell/Defs.hs:8:1
                 /home/trifon/fmisync/Courses/2019_20/FP_2019_20/sandbox/lectures/haskell/Defs.hs:20:1
   |
Compilation failed.
λ>