I have this list of type ([(Double,Double)],[(Double,Double)]). example list = ([(1.0,1.0), (2.0,1.0), (1.0,1.0), (1.0,3.0)],[(1.0,4.0), (1.0,5.0), (1.0,1.0), (1.0,2.0), (1.0,3.0), (1.0,4.0), (1.0,5.0)])
How would I access all the data after the fourth tuple (1.0, 3.0). I have already tried the tail function but doesn't seem to work. Thanks.
Well, for one, your list isn't a list, but a tuple :)
type MyData = (MyList, MyList) type MyList = [MyListElem] type MyListElem = (Double, Double) Now, accessing the 2nd list is simply snd.
snd :: (a,b) -> b So in your case:
snd :: MyData -> MyList Alternatively, using Lens, you can use a lens on that directly:
list ^. _2 
It's not a list, but a tuple of lists. In fact, a tuple of lists of tuples.
To get the second part of a tuple, use the snd command:
snd ([(1.0,1.0), (2.0,1.0), (1.0,1.0), (1.0,3.0)],[(1.0,4.0), (1.0,5.0), (1.0,1.0), (1.0,2.0), (1.0,3.0), (1.0,4.0), (1.0,5.0)]) This yields:
[(1.0,4.0),(1.0,5.0),(1.0,1.0),(1.0,2.0),(1.0,3.0),(1.0,4.0),(1.0,5.0)] From here on, you can continue to get the parts of the second list using tail or the !! operator.
For completeness, the first part of a tuple can be obtained using the fst command.
