[Haskell-cafe] simple Haskell question - List comprehensions

[Philip Müller]

Hi,

I'm just working through Hutton's "Programming in Haskell" and I found 
an exercise which I can't solve, although it looks simple. Maybe someone 
here could give me a hint?

Exercise:
Show how the single comprehension [(x,y) | x <- [1,2,3], y <- [4,5,6]] 
with two generators can be re-expressed using two comprehensions with 
single generators.
Hint: make use of the library function _concat_.

Thank you very much,
Philip