content: -- |
  -- Module      :  Data.Text.Prettyprint.Doc
  -- Copyright   :  Daan Leijen (c) 2000, http://www.cs.uu.nl/~daan
  --                Max Bolingbroke (c) 2008, http://blog.omega-prime.co.uk
  --                David Luposchainsky (c) 2016, http://github.com/quchen
  -- License     :  BSD-style (see the file LICENSE.md)
  -- Maintainer  :  David Luposchainsky <dluposchainsky (λ) google>
  -- Stability   :  experimental
  -- Portability :  portable
  --
  -- = Overview
  --
  -- This module defines a prettyprinter to format text in a flexible and
  -- convenient way. The idea is to combine a 'Doc'ument out of many small
  -- components, then using a layouter to convert it to an easily renderable
  -- 'SimpleDocStream', which can then be rendered to a variety of formats, for
  -- example plain 'Text'.
  --
  -- The documentation consists of several parts:
  --
  --   1. Just below is some general information about the library.
  --   2. The actual library with extensive documentation and examples
  --   3. Migration guide for users familiar with (ansi-)wl-pprint
  --
  -- == Starting out
  --
  -- As a reading list for starters, some of the most commonly used functions in
  -- this module include '<>', 'hsep', '<+>', 'vsep', 'align', 'hang'. These cover
  -- many use cases already, and many other functions are variations or
  -- combinations of these.
  --
  -- = Simple example
  --
  -- Let’s prettyprint a simple Haskell type definition. First, intersperse @->@
  -- and add a leading @::@,
  --
  -- >>> let prettyType = align . sep . zipWith (<+>) ("::" : repeat "->")
  --
  -- The 'sep' function is one way of concatenating documents, there are multiple
  -- others, e.g. 'vsep', 'cat' and 'fillSep'. In our case, 'sep' space-separates
  -- all entries if there is space, and newlines if the remaining line is too
  -- short.
  --
  -- Second, prepend the name to the type,
  --
  -- >>> let prettyDecl n tys = pretty n <+> prettyType tys
  --
  -- Now we can define a document that contains some type signature:
  --
  -- >>> let doc = prettyDecl "example" ["Int", "Bool", "Char", "IO ()"]
  --
  -- This document can now be printed, and it automatically adapts to available
  -- space. If the page is wide enough (80 characters in this case), the
  -- definitions are space-separated,
  --
  -- >>> putDocW 80 doc
  -- example :: Int -> Bool -> Char -> IO ()
  --
  -- If we narrow the page width to only 20 characters, the /same document/
  -- renders vertically aligned:
  --
  -- >>> putDocW 20 doc
  -- example :: Int
  --         -> Bool
  --         -> Char
  --         -> IO ()
  --
  -- Speaking of alignment, had we not used 'align', the @->@ would be at the
  -- beginning of each line, and not beneath the @::@.
  --
  -- The 'Data.Text.Prettyprint.Doc.Util.putDocW' renderer used here is from
  -- "Data.Text.Prettyprint.Doc.Util".
  --
  -- = General workflow
  --
  -- @
  -- ╔══════════╗
  -- ║          ║                         ╭────────────────────╮
  -- ║          ║                         │ 'vsep', 'pretty', '<+>', │
  -- ║          ║                         │ 'nest', 'align', …     │
  -- ║          ║                         ╰─────────┬──────────╯
  -- ║          ║                                   │
  -- ║  Create  ║                                   │
  -- ║          ║                                   │
  -- ║          ║                                   ▽
  -- ║          ║                         ╭───────────────────╮
  -- ║          ║                         │        'Doc'        │
  -- ╠══════════╣                         │  (rich document)  │
  -- ║          ║                         ╰─────────┬─────────╯
  -- ║          ║                                   │
  -- ║          ║                                   │ Layout algorithms
  -- ║  Layout  ║                                   │ e.g. 'layoutPretty'
  -- ║          ║                                   ▽
  -- ║          ║                         ╭───────────────────╮
  -- ║          ║                         │  'SimpleDocStream'  │
  -- ╠══════════╣                         │ (simple document) │
  -- ║          ║                         ╰─────────┬─────────╯
  -- ║          ║                                   │
  -- ║          ║                                   ├─────────────────────────────╮
  -- ║          ║                                   │                             │ 'Data.Text.Prettyprint.Doc.Render.Util.SimpleDocTree.treeForm'
  -- ║          ║                                   │                             ▽
  -- ║          ║                                   │                     ╭───────────────╮
  -- ║          ║                                   │                     │ 'Data.Text.Prettyprint.Doc.Render.Util.SimpleDocTree.SimpleDocTree' │
  -- ║  Render  ║                                   │                     ╰───────┬───────╯
  -- ║          ║                                   │                             │
  -- ║          ║               ╭───────────────────┼─────────────────╮  ╭────────┴────────╮
  -- ║          ║               │                   │                 │  │                 │
  -- ║          ║               ▽                   ▽                 ▽  ▽                 ▽
  -- ║          ║       ╭───────────────╮   ╭───────────────╮   ╭───────────────╮   ╭───────────────╮
  -- ║          ║       │ ANSI terminal │   │  Plain 'Text'   │   │ other/custom  │   │     HTML      │
  -- ║          ║       ╰───────────────╯   ╰───────────────╯   ╰───────────────╯   ╰───────────────╯
  -- ║          ║
  -- ╚══════════╝
  -- @
  --
  -- = How the layout works
  --
  -- There are two key concepts to laying a document out: the available width, and
  -- 'group'ing.
  --
  -- == Available width
  --
  -- The page has a certain maximum width, which the layouter tries to not exceed,
  -- by inserting line breaks where possible. The functions given in this module
  -- make it fairly straightforward to specify where, and under what
  -- circumstances, such a line break may be inserted by the layouter, for example
  -- via the 'sep' function.
  --
  -- There is also the concept of /ribbon width/. The ribbon is the part of a line
  -- that is printed, i.e. the line length without the leading indentation. The
  -- layouters take a ribbon fraction argument, which specifies how much of a line
  -- should be filled before trying to break it up. A ribbon width of 0.5 in a
  -- document of width 80 will result in the layouter to try to not exceed @0.5*80 =
  -- 40@ (ignoring current indentation depth).
  --
  -- == Grouping
  --
  -- A document can be 'group'ed, which tells the layouter that it should attempt
  -- to collapse it to a single line. If the result does not fit within the
  -- constraints (given by page and ribbon widths), the document is rendered
  -- unaltered. This allows fallback definitions, so that we get nice results even
  -- when the original document would exceed the layout constraints.
  --
  -- = Things the prettyprinter /cannot/ do
  --
  -- Due to how the Wadler/Leijen algorithm is designed, a couple of things are
  -- unsupported right now, with a high possibility of having no sensible
  -- implementation without significantly changing the layout algorithm. In
  -- particular, this includes
  --
  --   * Leading symbols instead of just spaces for indentation, as used by the
  --     Linux @tree@ tool for example
  --   * Multi-column layouts, in particular tables with multiple cells of equal
  --     width adjacent to each other
  --
  -- = Some helpful tips
  --
  -- == Which kind of annotation should I use?
  --
  -- __Summary:__ Use semantic annotations for @'Doc'@, and after layouting map to
  -- backend-specific ones.
  --
  -- For example, suppose you want to prettyprint some programming language code.
  -- If you want keywords to be red, you should annotate the @'Doc'@ with a type
  -- that has a 'Keyword' field (without any notion of color), and then after
  -- layouting convert the annotations to map @'Keyword'@ to e.g. @'Red'@ (using
  -- @'reAnnotateS'@). The alternative that I /do not/ recommend is directly
  -- annotating the @'Doc'@ with 'Red'.
  --
  -- While both versions would superficially work equally well and would create
  -- identical output, the recommended way has two significant advantages:
  -- modularity and extensibility.
  --
  -- /Modularity:/ To change the color of keywords later, you have to touch one
  -- point, namely the mapping in @'reAnnotateS'@, where @'Keyword'@ is mapped to
  -- 'Red'. If you have @'annotate Red …'@ everywher, you’ll have to do a full
  -- text replacement, producing a large diff and touching lots of places for a
  -- very small change.
  --
  -- /Extensibility:/ Adding a different backend in the recommended version is
  -- simply adding another @'reAnnotateS'@ to convert the @'Doc'@ annotation to
  -- something else. On the other hand, if you have @'Red'@ as an annotation in
  -- the @'Doc'@ already and the other backend does not support anything red
  -- (think of plain text or a website where red doesn’t work well with the rest
  -- of the style), you’ll have to worry about what to map »redness« to, which has
  -- no canonical answer. Should it be omitted? What does »red« mean anyway –
  -- maybe keywords and variables are red, and you want to change only the color
  -- of variables?
  module Data.Text.Prettyprint.Doc (
      -- * Documents
      Doc,
  
      -- * Basic functionality
      Pretty(..),
      viaShow, unsafeViaShow,
      emptyDoc, nest, line, line', softline, softline', hardline, group, flatAlt,
  
      -- * Alignment functions
      --
      -- | The functions in this section cannot be described by Wadler's original
      -- functions. They align their output relative to the current output
      -- position - in contrast to @'nest'@ which always aligns to the current
      -- nesting level. This deprives these functions from being \'optimal\'. In
      -- practice however they prove to be very useful. The functions in this
      -- section should be used with care, since they are more expensive than the
      -- other functions. For example, @'align'@ shouldn't be used to pretty print
      -- all top-level declarations of a language, but using @'hang'@ for let
      -- expressions is fine.
      align, hang, indent, encloseSep, list, tupled,
  
      -- * Binary functions
      (<>), (<+>),
  
      -- * List functions
  
      -- | The 'sep' and 'cat' functions differ in one detail: when 'group'ed, the
      -- 'sep's replace newlines wich 'space's, while the 'cat's simply remove
      -- them. If you're not sure what you want, start with the 'sep's.
  
      concatWith,
  
      -- ** 'sep' family
      --
      -- | When 'group'ed, these will replace newlines with spaces.
      hsep, vsep, fillSep, sep,
      -- ** 'cat' family
      --
      -- | When 'group'ed, these will remove newlines.
      hcat, vcat, fillCat, cat,
      -- ** Others
      punctuate,
  
      -- * Reactive/conditional layouts
      --
      -- | Lay documents out differently based on current position and the page
      -- layout.
      column, nesting, width, pageWidth,
  
      -- * Filler functions
      --
      -- | Fill up available space
      fill, fillBreak,
  
      -- * General convenience
      --
      -- | Useful helper functions.
      plural, enclose, surround,
  
      -- * Bracketing functions
      --
      -- | Enclose documents in common ways.
      squotes, dquotes, parens, angles, brackets, braces,
  
      -- * Named characters
      --
      -- | Convenience definitions for common characters
      lparen, rparen, langle, rangle, lbrace, rbrace, lbracket, rbracket, squote,
      dquote, semi, colon, comma, space, dot, slash, backslash, equals, pipe,
  
      -- ** Annotations
      annotate,
      unAnnotate,
      reAnnotate,
      alterAnnotations,
      unAnnotateS,
      reAnnotateS,
      alterAnnotationsS,
  
      -- * Optimization
      --
      -- Render documents faster
      fuse, FusionDepth(..),
  
      -- * Layout
      --
      -- | Laying a 'Doc'ument out produces a straightforward 'SimpleDocStream'
      -- based on parameters such as page width and ribbon size, by evaluating how
      -- a 'Doc' fits these constraints the best. There are various ways to render
      -- a 'SimpleDocStream'. For the common case of rendering a 'SimpleDocStream'
      -- as plain 'Text' take a look at "Data.Text.Prettyprint.Doc.Render.Text".
      SimpleDocStream(..),
      PageWidth(..), LayoutOptions(..), defaultLayoutOptions,
      layoutPretty, layoutCompact, layoutSmart,
      removeTrailingWhitespace,
  
      -- * Migration guide
      --
      -- $migration
  ) where
  
  
  
  import Data.Text.Prettyprint.Doc.Internal
  import Data.Text.Prettyprint.Doc.Symbols.Ascii
  
  -- $setup
  --
  -- (Definitions for the doctests)
  --
  -- >>> :set -XOverloadedStrings
  -- >>> import Data.Text.Prettyprint.Doc.Render.Text
  -- >>> import Data.Text.Prettyprint.Doc.Util
  
  
  
  -- $migration
  --
  -- There are 3 main ways to migrate:
  --
  --   1. Direct: just replace the previous package and fix the errors
  --   2. Using a drop-in replacement mimicing the API of the former module, see
  --      the @prettyprinter-compat-<former package>@ packages
  --   3. Using a converter from the old @Doc@ type to the new one, see the
  --      @prettyprinter-convert-<former package>@ packages
  --
  -- If you're already familiar with (ansi-)wl-pprint, you'll recognize many
  -- functions in this module, and they work just the same way. However, a couple
  -- of definitions are missing:
  --
  --   - @char@, @string@, @double@, … – these are all special cases of the
  --     overloaded @'pretty'@ function.
  --   - @\<$>@, @\<$$>@, @\</>@, @\<//>@ are special cases of
  --     @'vsep'@, @'vcat'@, @'fillSep'@, @'fillCat'@ with only two documents.
  --   - If you need 'String' output, use the backends in the
  --     "Data.Text.Prettyprint.Doc.Render.String" module.
  --   - The /display/ functions are moved to the rendering submodules, for
  --     example conversion to plain 'Text' is in the
  --     "Data.Text.Prettyprint.Doc.Render.Text" module.
  --   - The /render/ functions are called /layout/ functions.
  --   - @SimpleDoc@ was renamed to @'SimpleDocStream'@, in order to make it
  --     clearer in the presence of @SimpleDocTree@.
  --   - Instead of providing an own colorization function for each
  --     color\/intensity\/layer combination, they have been combined in 'color',
  --     'colorDull', 'bgColor', and 'bgColorDull' functions, which can be found
  --     in the ANSI terminal specific @prettyprinter-ansi-terminal@ package.
  