Safe Haskell | None |
---|---|
Language | Haskell2010 |
QuasiQuoter for interpolated strings using Perl 6 syntax.
The q
form does one thing and does it well: It contains a multi-line string with
no interpolation at all:
{-# LANGUAGE QuasiQuotes, ExtendedDefaultRules #-} import Text.InterpolatedString.QQ2 (q) foo :: String --Text
,ByteString
etc also works foo = [q| Well here is a multi-line string! |]
Any instance of the IsString
class is permitted.
The qc
form interpolates curly braces: expressions inside #{} will be
directly interpolated if it's a Char
, String
, Text
or ByteString
, or
it will have show
called if it is not.
Escaping of '{' is done with backslash.
For interpolating numeric expressions without an explicit type signature, use the ExtendedDefaultRules lanuage pragma, as shown below:
{-# LANGUAGE QuasiQuotes, ExtendedDefaultRules #-} import Text.InterpolatedString.QQ2 (qc) bar :: String bar = [qc| Well {6 * 7} |]
bar will have the value " Well hello there 42 ".
If you want control over how show
works on your types, define a custom
ShowQ
instance:
For example, this instance allows you to display interpolated lists of strings as a sequence of words, removing those pesky brackets, quotes, and escape sequences.
{-# LANGUAGE FlexibleInstances #-} import Text.InterpolatedString.QQ2 (qc, ShowQ(..)) instance ShowQ [String] where showQ = unwords
qc
permits output to any types with both IsString
and Monoid
instances.
{--} import Text.InterpolatedString.QQ2 (qc) import Data.Text (Text) import Data.ByteString.Char8 (ByteString) qux :: ByteString qux = [qc| This will convert {"ByteString" :: ByteString} |]
Synopsis
- qc :: QuasiQuoter
- q :: QuasiQuoter
- class ShowQ a where
Documentation
qc :: QuasiQuoter Source #
QuasiQuoter for interpolating '{expr}' into a string literal. The pattern portion is undefined.
q :: QuasiQuoter Source #
QuasiQuoter for a non-interpolating string literal. The pattern portion is undefined.
A class for types that use special interpolation rules.
Instances of ShowQ
that are also instances of IsString
should obey the
following law:
fromString (showQ s) == s
because this library relies on this fact to optimize away needless string conversions.
Instances
ShowQ Char Source # | |
Show a => ShowQ a Source # | |
Defined in Text.InterpolatedString.QQ2 | |
ShowQ String Source # | |
ShowQ ByteString Source # | |
Defined in Text.InterpolatedString.QQ2 showQ :: ByteString -> String Source # | |
ShowQ ByteString Source # | |
Defined in Text.InterpolatedString.QQ2 showQ :: ByteString -> String Source # | |
ShowQ Text Source # | |
ShowQ Text Source # | |