Haskell QuasiQuotes Text.RawString.QQ 插值

Question

我怎样才能像这样插值:

{-# LANGUAGE QuasiQuotes #-}
import Text.RawString.QQ

myText :: Text -> Text
myText myVariable = [r|line one
line two
line tree
${ myVariable }
line five|]

myText' :: Text
myText' = myText "line four"

${ myVariable } 打印为文字，而不是插值，在这种情况下我可以做类似的插值吗？

Answer 1

准引用器 r 不实现插值。它仅适用于原始字符串。你需要另一个准引用者。

完整代码:

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}

import Data.Text (Text)
import Text.RawString.QQ (r)
import NeatInterpolation (text)

rQuote :: Text -> Text
rQuote myVariable = [r|line one
line two
line tree
${ myVariable }
line five|]

neatQuote :: Text -> Text
neatQuote myVariable = [text|line one
line two
line tree
$myVariable
line five|]

rText, neatText :: Text
rText    = rQuote    "line four"
neatText = neatQuote "line four"

在ghci中:

*Main> import Data.Text.IO as TIO
*Main TIO> TIO.putStrLn rText
line one
line two
line tree
${ myVariable }
line five
*Main TIO> TIO.putStrLn neatText
line one
line two
line tree
line four
line five