Hi Angus,
you need to put the parentheses around the pattern x:xs because the
application reverse' has priority over (:) , so the statement is the
same as
(reverse' x):xs = reverse' xs ++ [x]
and results the error.
-- Denis.
On Mon, Dec 23, 2013 at 12:57 PM, Angus Comber
Eg for a definition of reverse:
reverse' :: [a] -> [a] reverse' [] = [] reverse' (x:xs) = reverse' xs ++ [x]
In the last line of the definition, x is an element in the list (the first element) and xs represents the remainder of the list.
so if list was [1,2,3] then x is 1 and xs is [2,3]
Why are the brackets required? And what do they signify?
Eg reverse' x:xs = reverse' xs ++ [x] results in a parse error.
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