Haskell - How to get a List of Tuples with certain combinations

Question

Is there a way to create a list of tuples with a certain pattern?

I have following inputs for example:

a = 100

b = [10,20,30]

c = ['a','b','c','d','e','f','g']

And I would like to have following Output:

[(100,10,'a'),(100,10,'b'),(100,10,'c'),(100,10,'d'),(100,10,'e'),(100,10,'f'),(100,10,'g'),
 (100,20,'a'),(100,20,'b'),(100,20,'c'),(100,20,'d'),(100,20,'e'),(100,20,'f'),(100,20,'g'),
 (100,30,'a'),(100,30,'b'),(100,30,'c'),(100,30,'d'),(100,30,'e'),(100,30,'f'),(100,30,'g')]

I think if I only had a and b for example I would do:

makeTuple :: Int -> [Int] -> [(Int,Int)]
makeTuple _ [] = []
makeTuple i (x:xs) = [(i,x)] ++ makeTuple i xs

This would give me:

[(100,10),(100,20),(100,30)]

Im not sure how I could make it work with 3 Inputs .

Answer 1

List comprehensions can do it nicely:

[(a, x, y) | x <- b, y <- c]