Merge branch 'exo'

From slide 30 to slide 37

listfct.hs

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+-- Reverse list order
+myexchanger xs zs = case xs of
+	[] -> zs
+	y:ys -> myexchanger ys (y:zs)
+
+myreverse xs = myexchanger xs []
+
+-- Delete the first item
+mydelete l y = case l of
+	[] -> []
+	x:xs -> if x == y then xs else x:(mydelete xs y)
+
+-- Find the maximum
+mymaximum l = mymaximumof l 0
+
+mymaximumof l x = case l of
+	[] -> x
+	y:ys -> if y > x then mymaximumof ys y else mymaximumof ys x
+
+-- Sort the list
+trimax l = if l == []
+	then []
+	else let y = mymaximum l in y:(trimax (mydelete l y))

myflip.hs

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+myflip::(a -> a -> b) -> a -> a -> b
+
+myflip f a1 a2 = f a2 a1

tripy.hs

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+square n = [(x, x * x) | x <- [1..n], x * x > 10]
+
+tripy n = [(a, b, c) | a <- [0..(div n 3)], b <- [(a + 1)..(div n 2)], c <- [(b + 1)..n], a^2 + b^2 == c^2, a + b + c == n]