isAscii package:text

isAscii :: Text -> Bool
text Data.Text
O(n) Test whether Text contains only ASCII code-points (i.e. only U+0000 through U+007F). This is a more efficient version of all isAscii. 
>>> isAscii ""
True

>>> isAscii "abc\NUL"
True

>>> isAscii "abcd€"
False

isAscii t == all (< '\x80') t
isAscii :: Text -> Bool
text Data.Text.Lazy
O(n) Test whether Text contains only ASCII code-points (i.e. only U+0000 through U+007F). This is a more efficient version of all isAscii. 
>>> isAscii ""
True

>>> isAscii "abc\NUL"
True

>>> isAscii "abcd€"
False

isAscii t == all (< '\x80') t