Singleton list confusion
Why do Haskell newcomers frequently believe, that list variables must be enclosed in brackets?
People sometimes write argument patterns like [x], hoping that x will assume all values of a list successively.
Example:
case xs of [x] -> [f x]
although they meant
[f x | x <- xs]
or just map f xs.
It seems like they expect some kind of list comprehension.
However, if there wouldn't be a special list notation and if there wouldn't be the special syntax for the list type constructor (thus we must write [a] instead of List a),
then there would be certainly less confusion.
See for example Haskell-Cafe about testing for same characters in lists of strings, Pattern match failure