Turtle.Line

Documentation

data Line

A line of text (does not contain newlines).

Instances

Eq Line

Methods

(==) :: Line -> Line -> Bool

(/=) :: Line -> Line -> Bool

Ord Line

Methods

compare :: Line -> Line -> Ordering

(<) :: Line -> Line -> Bool

(<=) :: Line -> Line -> Bool

(>) :: Line -> Line -> Bool

(>=) :: Line -> Line -> Bool

max :: Line -> Line -> Line

min :: Line -> Line -> Line

Show Line

Methods

showsPrec :: Int -> Line -> ShowS

show :: Line -> String

showList :: [Line] -> ShowS

IsString Line

Methods

fromString :: String -> Line

Monoid Line

Methods

mempty :: Line

mappend :: Line -> Line -> Line

mconcat :: [Line] -> Line

lineToText :: Line -> Text

Convert a line to a text value.

textToLines :: Text -> NonEmpty Line

Split text into lines. The inverse of linesToText.

linesToText :: [Line] -> Text

Merge lines into a single text value.

textToLine :: Text -> Maybe Line

Try to convert a text value into a line. Precondition (checked): the argument does not contain newlines.

unsafeTextToLine :: Text -> Line

Convert a text value into a line. Precondition (unchecked): the argument does not contain newlines.

data NewlineForbidden

The NewlineForbidden exception is thrown when you construct a Line using an overloaded string literal or by calling fromString explicitly and the supplied string contains newlines. This is a programming error to do so: if you aren't sure that the input string is newline-free, do not rely on the IsString Line instance.

When debugging, it might be useful to look for implicit invocations of fromString for Line:

>>> sh (do { line <- "Hello\nWorld"; echo line })
*** Exception: NewlineForbidden

In the above example, echo expects its argument to be a Line, thus line :: Line. Since we bind line in Shell, the string literal "Hello\nWorld" has type Shell Line. The IsString (Shell Line) instance delegates the construction of a Line to the IsString Line instance, where the exception is thrown.

To fix the problem, use textToLines:

>>> sh (do { line <- select (textToLines "Hello\nWorld"); echo line })
Hello
World

Constructors

NewlineForbidden

Instances

Show NewlineForbidden

Methods

showsPrec :: Int -> NewlineForbidden -> ShowS

show :: NewlineForbidden -> String

showList :: [NewlineForbidden] -> ShowS

Exception NewlineForbidden

Methods

toException :: NewlineForbidden -> SomeException

fromException :: SomeException -> Maybe NewlineForbidden

displayException :: NewlineForbidden -> String