Checking for equality in lists in SML
Question
i want to write a function that checks for equality of lists in SML for instance : [1,2,3]=[1,2,3]; val it = true : bool
So instead of writing down the whole thing, i want to make a function that takes two predefined lists, and compare them, so that if list01 = [1,2,3] and list09 = [1,2,3] then fun equal (list01,list09); will return -val it = true : bool;
Thanx in advance for any ideas/hints and help :)
Solution
Here is a not checked sample:
fun compare ([], []) = true # both empty
| compare (x::xs, y::ys) = (x = y) and compare(xs,ys)
| compare (_, _) = false # different lengths
OTHER TIPS
You seem to be aware that =
works on lists, so (as I already said in my comment) I don't see why you need to define an equal
function.
That being said, you can just write:
fun equal (a, b) = (a = b);
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