The "Pretty" renderer generates incorrect output #111

nad · 2017-08-30T09:52:44Z

Consider the following code:

{-# LANGUAGE OverloadedStrings #-}

module Test where

import Text.Blaze.Html5 as H
import Text.Blaze.Html5.Attributes as A
import Text.Blaze.Html.Renderer.Pretty

example =
  putStr $ renderHtml $ docTypeHtml $ do
    H.head $ do
      meta ! charset "utf-8"
      H.title "Test"
    body $ pre $ do
      "Text"
      H.a $ "Text inside tag"
      "More text"

The resulting output:

<!DOCTYPE HTML>

<html>
    <head>
        <meta charset="utf-8">
        <title>
            Test
        </title>
    </head>
    <body>
        <pre>
            Text
            <a>
                Text inside tag
            </a>
            More text
        </pre>
    </body>
</html>

When the pre tag is used whitespace is significant, so I consider the output above to be incorrect. If the String renderer is used, then the output is better:

<!DOCTYPE HTML>
<html><head><meta charset="utf-8"><title>Test</title></head><body><pre>Text<a>Text inside tag</a>More text</pre></body></html>

The xhtml library handles this problem by inserting whitespace inside the tags (</a\n >). Perhaps you could do the same. (Or at least document that the pretty output is broken.)

The text was updated successfully, but these errors were encountered:

Profpatsch · 2024-03-17T16:32:11Z

I stumbled over this as well. I guess it could be improved by having a list of tags where it shouldn’t create linebreaks.

I also noticed that when you have nested Append constructors, it will add linebreaks, leading to extra spaces in appended Content constructors (e.g. if you have Append (Content "foo") (Content "bar") it renders as foo bar instead of foobar.

This is especially crucial for https://hackage.haskell.org/package/ihp-hsx, which creates Appends for interpolated variables, so if I interpolate say let x = "x" in [hsx|foo ({x})|] the result will be "foo ( x )" instead of "foo (x)".

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The "Pretty" renderer generates incorrect output #111

The "Pretty" renderer generates incorrect output #111

nad commented Aug 30, 2017 •

edited

Profpatsch commented Mar 17, 2024

The "Pretty" renderer generates incorrect output #111

The "Pretty" renderer generates incorrect output #111

Comments

nad commented Aug 30, 2017 • edited

Profpatsch commented Mar 17, 2024

nad commented Aug 30, 2017 •

edited