Text.PrettyPrint.Boxes

A pretty-printing library for laying out text in two dimensions, using a simple box model.

Constructing boxes

data Box

The basic data type. A box has a specified size and some sort of contents.

Instances

Show Box

IsString Box

Convenient ability to use bare string literals as boxes.

nullBox :: Box

The null box, which has no content and no size. It is quite useless.

emptyBox :: Int -> Int -> Box

emptyBox r c is an empty box with r rows and c columns. Useful for effecting more fine-grained positioning of other boxes, by inserting empty boxes of the desired size in between them.

char :: Char -> Box

A 1x1 box containing a single character.

text :: String -> Box

A (1 x len) box containing a string of length len.

para :: Alignment -> Int -> String -> Box

para algn w t is a box of width w, containing text t, aligned according to algn, flowed to fit within the given width.

columns :: Alignment -> Int -> Int -> String -> [Box]

columns w h t is a list of boxes, each of width w and height at most h, containing text t flowed into as many columns as necessary.

Layout of boxes

(<>) :: Box -> Box -> Box

Paste two boxes together horizontally, using a default (top) alignment.

(<+>) :: Box -> Box -> Box

Paste two boxes together horizontally with a single intervening column of space, using a default (top) alignment.

hcat :: Alignment -> [Box] -> Box

Glue a list of boxes together horizontally, with the given alignment.

hsep :: Int -> Alignment -> [Box] -> Box

hsep sep a bs lays out bs horizontally with alignment a, with sep amount of space in between each.

(//) :: Box -> Box -> Box

Paste two boxes together vertically, using a default (left) alignment.

(/+/) :: Box -> Box -> Box

Paste two boxes together vertically with a single intervening row of space, using a default (left) alignment.

vcat :: Alignment -> [Box] -> Box

Glue a list of boxes together vertically, with the given alignment.

vsep :: Int -> Alignment -> [Box] -> Box

vsep sep a bs lays out bs vertically with alignment a, with sep amount of space in between each.

punctuateH :: Alignment -> Box -> [Box] -> Box

punctuateH a p bs horizontally lays out the boxes bs with a copy of p interspersed between each.

punctuateV :: Alignment -> Box -> [Box] -> Box

A vertical version of punctuateH.

Alignment

data Alignment

Data type for specifying the alignment of boxes.

Instances

Eq Alignment

Read Alignment

Show Alignment

left :: Alignment

Align boxes to the left.

right :: Alignment

Align boxes to the right.

top :: Alignment

Align boxes along their tops.

bottom :: Alignment

Align boxes along their bottoms.

center1 :: Alignment

Align boxes centered, but biased to the left/top in case of unequal parities.

center2 :: Alignment

Align boxes centered, but biased to the right/bottom in case of unequal parities.

moveLeft :: Int -> Box -> Box

Move a box left by putting it in a larger box with extra columns, aligned left. Note that the name of this function is something of a white lie, as this will only result in the box being moved left by the specified amount if it is already in a larger right-aligned context.

moveRight :: Int -> Box -> Box

Move a box right by putting it in a larger box with extra columns, aligned right. See the disclaimer for moveLeft.

moveUp :: Int -> Box -> Box

Move a box "up" by putting it in a larger box with extra rows, aligned to the top. See the disclaimer for moveLeft.

moveDown :: Int -> Box -> Box

Move a box down by putting it in a larger box with extra rows, aligned to the bottom. See the disclaimer for moveLeft.

alignHoriz :: Alignment -> Int -> Box -> Box

alignHoriz algn n bx creates a box of width n, with the contents and height of bx, horizontally aligned according to algn.

alignVert :: Alignment -> Int -> Box -> Box

alignVert algn n bx creates a box of height n, with the contents and width of bx, vertically aligned according to algn.

align :: Alignment -> Alignment -> Int -> Int -> Box -> Box

align ah av r c bx creates an r x c box with the contents of bx, aligned horizontally according to ah and vertically according to av.

Inspecting boxes

rows :: Box -> Int

cols :: Box -> Int

Rendering boxes

render :: Box -> String

Render a Box as a String, suitable for writing to the screen or a file.

printBox :: Box -> IO ()

A convenience function for rendering a box to stdout.