{-# LANGUAGE CPP, OverloadedStrings, NoImplicitPrelude, UnicodeSyntax #-}
#if __GLASGOW_HASKELL__ >= 704
{-# LANGUAGE Safe #-}
#endif
--------------------------------------------------------------------------------
-- |
-- Module : Data.String.Combinators
-- Copyright : (c) 2009-2011 Bas van Dijk
-- License : BSD-style (see the file LICENSE)
-- Maintainer : Bas van Dijk <v.dijk.bas@gmail.com>
--
--------------------------------------------------------------------------------
module Data.String.Combinators
( -- * Combining
(<>)
, mid
, (<+>)
, ($$)
, intercalate
, hcat
, unwords
, unlines
, punctuate
-- * Wrapping in delimiters
, between
, parens
, thenParens
, brackets
, braces
, angleBrackets
, quotes
, doubleQuotes
-- * From characters
, char
, semi
, colon
, comma
, space
, newline
, equals
, lparen
, rparen
, lbrack
, rbrack
, lbrace
, rbrace
, labrack
, rabrack
-- * From showable values
, fromShow
, int
, integer
, float
, double
, rational
) where
--------------------------------------------------------------------------------
-- Imports
--------------------------------------------------------------------------------
-- from base:
import Data.List ( foldr )
import Data.Bool ( Bool(False, True) )
import Data.Char ( Char )
import Data.Function ( id )
import Data.Int ( Int )
import Data.Ratio ( Rational )
import Data.String ( IsString, fromString )
import Data.Monoid ( Monoid, mempty, mappend )
import Text.Show ( Show, show )
import Prelude ( Integer, Float, Double )
-- from base-unicode-symbols
import Data.Function.Unicode ( (∘) )
--------------------------------------------------------------------------------
-- * Combining
--------------------------------------------------------------------------------
-- | Put two string-likes besides eachother.
--
-- Note that: @'<>' = 'mappend'@.
(<>) ∷ Monoid s ⇒ s → s → s
(<>) = mappend
-- | @mid m x y@ Puts @x@ and @y@ around @m@.
--
-- Note that: @mid m x y = 'between' x y m@.
mid ∷ Monoid s ⇒ s → (s → s → s)
mid m x y = between x y m
-- | Put two string-likes besides eachother separated by a 'space'.
(<+>) ∷ (Monoid s, IsString s) ⇒ s → s → s
(<+>) = mid space
-- | Put two string-likes above eachother (separated by a 'newline').
($$) ∷ (Monoid s, IsString s) ⇒ s → s → s
($$) = mid newline
infixl 6 <>
infixl 6 <+>
infixl 5 $$
{-| Combine the string-likes with a given function.
@intercalate f [s1, ... sn] = s1 \`f\` (s2 \`f\` (... (sn-1 \`f\` sn)))@
-}
intercalate ∷ Monoid s ⇒ (s → s → s) → [s] → s
intercalate f = go
where
go [] = mempty
go (s:[]) = s
go (s:ss) = s `f` go ss
-- | List version of '<>'.
--
-- Note that: @hcat = 'intercalate' ('<>')@.
hcat ∷ Monoid s ⇒ [s] → s
hcat = intercalate (<>)
-- | List version of '<+>'.
--
-- Note that: @unwords = 'intercalate' ('<+>')@.
unwords ∷ (Monoid s, IsString s) ⇒ [s] → s
unwords = intercalate (<+>)
-- | List version of '$$'.
--
-- Note that: @unlines = foldr ('$$') mempty@
unlines ∷ (Monoid s, IsString s) ⇒ [s] → s
unlines = foldr ($$) mempty
-- | @punctuate p [s1, ... sn] = [s1 '<>' p, s2 '<>' p, ... sn-1 '<>' p, sn]@.
--
-- (Idea and implementation taken from the @pretty@ package.)
punctuate ∷ (Monoid s) ⇒ s → [s] → [s]
punctuate _ [] = []
punctuate p (d:ds) = go d ds
where
go d' [] = [d']
go d' (e:es) = (d' <> p) : go e es
--------------------------------------------------------------------------------
-- * Wrapping in delimiters
--------------------------------------------------------------------------------
-- | @between b c s@ wraps the string-like @s@ between @b@ and @c@.
between ∷ (Monoid s) ⇒ s → s → (s → s)
between open close = \x -> open <> x <> close
-- | Wrap a string-like in @(...)@.
parens ∷ (Monoid s, IsString s) ⇒ s → s
parens = between "(" ")"
-- | Wrap a string-like in @[...]@.
brackets ∷ (Monoid s, IsString s) ⇒ s → s
brackets = between "[" "]"
-- | Wrap a string-like in @{...}@.
braces ∷ (Monoid s, IsString s) ⇒ s → s
braces = between "{" "}"
-- | Wrap a string-like in @\<...\>@.
angleBrackets ∷ (Monoid s, IsString s) ⇒ s → s
angleBrackets = between "<" ">"
-- | Wrap a string-like in @\'...\'@.
quotes ∷ (Monoid s, IsString s) ⇒ s → s
quotes = between "'" "'"
-- | Wrap a string-like in @\"...\"@.
doubleQuotes ∷ (Monoid s, IsString s) ⇒ s → s
doubleQuotes = between "\"" "\""
{-| Like @showParen@ conditionally wraps a string-like in @(...)@
This function is supposed to be used infix as in:
@(precedence >= 10) \`thenParens\` (\"fun\" \<+\> \"arg\")@
-}
thenParens ∷ (Monoid s, IsString s) ⇒ Bool → s → s
thenParens True = parens
thenParens False = id
--------------------------------------------------------------------------------
-- * From characters
--------------------------------------------------------------------------------
-- | Convert a character to a string-like.
char ∷ IsString s ⇒ Char → s
char c = fromString [c]
-- | A ';' character.
semi ∷ IsString s ⇒ s
semi = char ';'
-- | A ':' character.
colon ∷ IsString s ⇒ s
colon = char ':'
-- | A ',' character.
comma ∷ IsString s ⇒ s
comma = char ','
-- | A ' ' character.
space ∷ IsString s ⇒ s
space = char ' '
-- | A '\n' character.
newline ∷ IsString s ⇒ s
newline = char '\n'
-- | A '=' character.
equals ∷ IsString s ⇒ s
equals = char '='
-- | A '(' character.
lparen ∷ IsString s ⇒ s
lparen = char '('
-- | A ')' character.
rparen ∷ IsString s ⇒ s
rparen = char ')'
-- | A '[' character.
lbrack ∷ IsString s ⇒ s
lbrack = char '['
-- | A ']' character.
rbrack ∷ IsString s ⇒ s
rbrack = char ']'
-- | A '{' character.
lbrace ∷ IsString s ⇒ s
lbrace = char '{'
-- | A '}' character.
rbrace ∷ IsString s ⇒ s
rbrace = char '}'
-- | A \'<\' character.
labrack ∷ IsString s ⇒ s
labrack = char '<'
-- | A \'>\' character.
rabrack ∷ IsString s ⇒ s
rabrack = char '>'
--------------------------------------------------------------------------------
-- * From showable values
--------------------------------------------------------------------------------
-- | Convert a @Show@able value to a string-like.
fromShow ∷ (Show α, IsString s) ⇒ α → s
fromShow = fromString ∘ show
-- | Convert an @Int@ to a string-like.
int ∷ IsString s ⇒ Int → s
int = fromShow
-- | Convert an @Integer@ to a string-like.
integer ∷ IsString s ⇒ Integer → s
integer = fromShow
-- | Convert a @Float@ to a string-like.
float ∷ IsString s ⇒ Float → s
float = fromShow
-- | Convert a @Double@ to a string-like.
double ∷ IsString s ⇒ Double → s
double = fromShow
-- | Convert a @Rational@ to a string-like.
rational ∷ IsString s ⇒ Rational → s
rational = fromShow