*Main> :t add' 1
add' 1 :: Int -> Int
*Main> add' 1

<interactive>:4:1: error:
    • No instance for (Show (Int -> Int)) arising from a use of ‘print’
        (maybe you haven't applied a function to enough arguments?)
    • In a stmt of an interactive GHCi command: print it
*Main> add' 1 2 
3
*Main> :t (\ x y -> x + y) 1
(\ x y -> x + y) 1 :: Num a => a -> a
*Main> (\ x y -> x + y) 1 2
3
*Main> :t (+)
(+) :: Num a => a -> a -> a
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> myLength "abcdefg"
7
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> myLength' "ab"
2
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> append [1,2,3] [4,5,6]
[1,2,3,4,5,6]
*Main> append [] [4,5,6]
[4,5,6]
*Main> append [1,2,3] []
[1,2,3]
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> append' [1,2,3] [4,5,6]
[1,2,3,4,5,6]
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> zip' [1,2,3] "abc"
[(1,'a'),(2,'b'),(3,'c')]
*Main> zip' [1,2,3] "ab"
[(1,'a'),(2,'b')*** Exception: lec2.hs:(65,1)-(66,40): Non-exhaustive patterns in function zip'

*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> zip' [1,2,3] "ab"
[(1,'a'),(2,'b')]
*Main> zip' [1,2,3] "abc"
[(1,'a'),(2,'b'),(3,'c')]
*Main> zip'' [1,2,3] "ab"

<interactive>:27:1: error:
    • Variable not in scope: zip'' :: [Integer] -> [Char] -> t
    • Perhaps you meant ‘zip'’ (line 65)
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> zip'' [1,2,3] "ab"
[(1,'a'),(2,'b')]
*Main> zip'' [1,2,3] "abc"
[(1,'a'),(2,'b'),(3,'c')]
*Main> 30 `mod` 4
2
*Main> (71+72+73+28) `mod` 4
0
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> myReverse [1,2,3,4,5]
[5,4,3,2,1]
*Main> myReverse' [1,2,3,4,5] []

<interactive>:5:1: error:
    • Couldn't match expected type ‘[a0] -> t’
                  with actual type ‘[Integer]’
    • The function ‘myReverse'’ is applied to two arguments,
      but its type ‘[Integer] -> [Integer]’ has only one
      In the expression: myReverse' [1, 2, 3, 4, ....] []
      In an equation for ‘it’: it = myReverse' [1, 2, 3, ....] []
    • Relevant bindings include it :: t (bound at <interactive>:5:1)
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )

lec2.hs:109:1: error:
    Duplicate type signatures for ‘myReverse'’
    at lec2.hs:81:1-10
       lec2.hs:109:1-10
    |
109 | myReverse' :: [a] -> [a]
    | ^^^^^^^^^^

lec2.hs:110:1: error:
    Multiple declarations of ‘myReverse'’
    Declared at: lec2.hs:82:1
                 lec2.hs:110:1
    |
110 | myReverse' = undefined
    | ^^^^^^^^^^
Failed, no modules loaded.
Prelude> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> myReverse' [1,2,3,4,5] []
[5,4,3,2,1]
*Main> :r
[1 of 1] Compiling Main             ( lec2.hs, interpreted )
Ok, one module loaded.
*Main> [1 .. 10 ]
[1,2,3,4,5,6,7,8,9,10]
*Main> myMap (\ x -> x + 2) [1 .. 10]
[3,4,5,6,7,8,9,10,11,12]
*Main> myMap (\ x -> "x" ++ ",") "abcdefg"
["x,","x,","x,","x,","x,","x,","x,"]
*Main> myMap (\ x -> x : ",") "abcdefg"
["a,","b,","c,","d,","e,","f,","g,"]
*Main> :t concat
concat :: Foldable t => t [a] -> [a]
*Main> concat (myMap (\ x -> x : ",") "abcdefg")
"a,b,c,d,e,f,g,"
*Main>