99 haskells

1.hs

-- get last item in a list
myLast [] = error "out of range"
myLast (x : []) = x
myLast (_ : r) = myLast r

main = do
    putStrLn(show(myLast [1,2,3]))

2.hs

-- function to get second to last item in a list
mySTLast [] = error "out of range"
mySTLast (_ : []) = error "out of range"
mySTLast (x : _ : []) = x
mySTLast (_ : r) = mySTLast r

main = do
    putStrLn (show (mySTLast [1,2,3]))
    putStrLn (show (mySTLast [1]))

3.hs

-- function to get an element at an arbirtary position in a list
-- this function is 1 indexed
elementAt [] _ = error "Index out of bounds"
elementAt (x : _) 1 = x
elementAt (_ : r) n = elementAt r (n-1)

main = do
    putStrLn (show (elementAt [1,2,3] 2))

4.hs

-- get the length of a list
-- accumulates the length in an inner function as it eats elements
myLength l = len' l 0
  where
    len' [] n = n
    len' (_:r) n = len' r (n+1)

main = do
    x <- return (myLength [1,2,3])
    putStrLn(show x)
    x <- return (myLength "hello pooperface")
    putStrLn(show x)

5.hs

-- reverse a list
-- this accumulates a reversed list as it goes in an inner function
myReverse l = reverse' l []
  where
    reverse' [] reversed = reversed
    reverse' (e:r) reversed = reverse' r (e:reversed)

main = do
    putStrLn(show (myReverse [1,2,3,4,5]))

Solutions to problems from this:
https://wiki.haskell.org/H-99:_Ninety-Nine_Haskell_Problems