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Alternative fix for #205 #283

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a5342e4
Add performance test for #205
sjakobi Dec 5, 2025
c584f60
Fix layoutSmart regression from blank-line indentation
sjakobi Mar 30, 2026
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58 changes: 46 additions & 12 deletions prettyprinter/src/Prettyprinter/Internal.hs
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -1895,6 +1895,7 @@
-> SimpleDocStream ann
layoutPretty (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
layoutWadlerLeijen
smartLine
(FittingPredicate
(\lineIndent currentColumn _initialIndentY sdoc ->
fits
Expand DownExpand Up@@ -1982,7 +1983,8 @@
-> Doc ann
-> SimpleDocStream ann
layoutSmart (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
layoutWadlerLeijen (FittingPredicate fits) pageWidth_
dropIndentationOnEmptyLines .
layoutWadlerLeijen plainLine (FittingPredicate fits) pageWidth_
where
-- Why doesn't layoutSmart simply check the entire document?
--
Expand All@@ -2001,7 +2003,14 @@
go w (SChar _ x) = go (w - 1) x
go w (SText l _t x) = go (w - l) x
go _ (SLine i x)
| minNestingLevel < i = go (lineLength - i) x -- TODO: Take ribbon width into account?! (#142)
| minNestingLevel < i =
let i' = case x of
SEmpty -> 0
SLine{} -> 0
_ -> i
in if minNestingLevel < i'

Check warning on line 2011 in prettyprinter/src/Prettyprinter/Internal.hs

View workflow job for this annotation

GitHub Actions/ hlint

Warning in layoutSmart in module Prettyprinter.Internal: Redundant if ▫︎ Found: "if minNestingLevel < i' then go (lineLength - i') x else True" ▫︎ Perhaps: "(not (minNestingLevel < i') || go (lineLength - i') x)"
then go (lineLength - i') x -- TODO: Take ribbon width into account?! (#142)
else True
| otherwise = True
go w (SAnnPush _ x) = go w x
go w (SAnnPop x) = go w x
Expand DownExpand Up@@ -2029,6 +2038,7 @@
layoutUnbounded :: Doc ann -> SimpleDocStream ann
layoutUnbounded =
layoutWadlerLeijen
smartLine
(FittingPredicate
(\_lineIndent _currentColumn _initialIndentY sdoc -> not (failsOnFirstLine sdoc)))
Unbounded
Expand All@@ -2046,13 +2056,45 @@
SAnnPush _ s -> go s
SAnnPop s -> go s

plainLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
plainLine i x = SLine i x

smartLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
smartLine i x =
let i' = case x of
SEmpty -> 0
SLine{} -> 0
_ -> i
in SLine i' x

-- | Remove indentation that would otherwise survive on empty lines.
dropIndentationOnEmptyLines :: SimpleDocStream ann -> SimpleDocStream ann
dropIndentationOnEmptyLines = go
where
go sds = case sds of
SFail -> SFail
SEmpty -> SEmpty
SChar c x -> SChar c (go x)
SText l t x -> SText l t (go x)
SLine i x ->
let x' = go x
i' = case x' of
SEmpty -> 0
SLine{} -> 0
_ -> i
in SLine i' x'
SAnnPush ann x -> SAnnPush ann (go x)
SAnnPop x -> SAnnPop (go x)

-- | The Wadler/Leijen layout algorithm
layoutWadlerLeijen
:: forall ann. FittingPredicate ann
:: forall ann. (Int -> SimpleDocStream ann -> SimpleDocStream ann)
-> FittingPredicate ann
-> PageWidth
-> Doc ann
-> SimpleDocStream ann
layoutWadlerLeijen
mkLine
(FittingPredicate fits)
pageWidth_
doc
Expand All@@ -2073,15 +2115,7 @@
Empty -> best nl cc ds
Char c -> let !cc' = cc+1 in SChar c (best nl cc' ds)
Text l t -> let !cc' = cc+l in SText l t (best nl cc' ds)
Line -> let x = best i i ds
-- Don't produce indentation if there's no
-- following text on the same line.
-- This prevents trailing whitespace.
i' = case x of
SEmpty -> 0
SLine{} -> 0
_ -> i
in SLine i' x
Line -> mkLine i (best i i ds)
FlatAlt x _ -> best nl cc (Cons i x ds)
Cat x y -> best nl cc (Cons i x (Cons i y ds))
Nest j x -> let !ij = i+j in best nl cc (Cons ij x ds)
Expand Down
10 changes: 10 additions & 0 deletions prettyprinter/test/Testsuite/Main.hs
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -53,6 +53,8 @@ tests = testGroup "Tests"
groupingPerformance
, testCase "fillSep performance"
fillSepPerformance
, testCase "Issue 205"
issue205
]
, testGroup "Regression tests"
[ testCase "layoutSmart: softline behaves like a newline (#49)"
Expand DownExpand Up@@ -285,6 +287,14 @@ fillSepPerformance = docPerformanceTest (pathological 1000)
pathological :: Int -> Doc ann
pathological n = iterate (\x -> fillSep ["a", x <+> "b"] ) "foobar" !! n

issue205 :: Assertion
issue205 = do
let doc = fillSep (replicate 30 (sep ["abc", "xyz" :: Doc ()]))
t = renderStrict (layoutSmart defaultLayoutOptions doc)
timeout 1000000 (evaluate t) >>= \t' -> case t' of
Nothing -> assertFailure "Timeout!"
Just _success -> pure ()

regressionLayoutSmartSoftline :: Assertion
regressionLayoutSmartSoftline
= let doc = "a" <> softline <> "b"
Expand Down
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Alternative fix for #205 by sjakobi · Pull Request #283 · haskell-prettyprinter/prettyprinter · GitHub
Skip to content
Alternative fix for #205#283

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Alternative fix for #205
#283
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a5342e4

Add performance test for #205


sjakobi Dec 5, 2025
c584f60

Fix layoutSmart regression from blank-line indentation


sjakobi Mar 30, 2026

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58 changes: 46 additions & 12 deletions
prettyprinter/src/Prettyprinter/Internal.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1895,6 +1895,7 @@
 -> SimpleDocStream ann
layoutPretty (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\lineIndent currentColumn _initialIndentY sdoc ->
 fits
Expand DownExpand Up@@ -1982,7 +1983,8 @@
 -> Doc ann
 -> SimpleDocStream ann
layoutSmart (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen (FittingPredicate fits) pageWidth_
 dropIndentationOnEmptyLines .
 layoutWadlerLeijen plainLine (FittingPredicate fits) pageWidth_
 where
 -- Why doesn't layoutSmart simply check the entire document?
 --
Expand All@@ -2001,7 +2003,14 @@
 go w (SChar _ x) = go (w - 1) x
 go w (SText l _t x) = go (w - l) x
 go _ (SLine i x)
 | minNestingLevel < i = go (lineLength - i) x -- TODO: Take ribbon width into account?! (#142)
 | minNestingLevel < i =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in if minNestingLevel < i'

Check warning
on line 2011
in prettyprinter/src/Prettyprinter/Internal.hs

View workflow job for this annotation
GitHub Actions/ hlint
Warning in layoutSmart in module Prettyprinter.Internal: Redundant if ▫︎ Found: "if minNestingLevel < i' then go (lineLength - i') x else True" ▫︎ Perhaps: "(not (minNestingLevel < i') || go (lineLength - i') x)"
 then go (lineLength - i') x -- TODO: Take ribbon width into account?! (#142)
 else True
 | otherwise = True
 go w (SAnnPush _ x) = go w x
 go w (SAnnPop x) = go w x
Expand DownExpand Up@@ -2029,6 +2038,7 @@
layoutUnbounded :: Doc ann -> SimpleDocStream ann
layoutUnbounded =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\_lineIndent _currentColumn _initialIndentY sdoc -> not (failsOnFirstLine sdoc)))
 Unbounded
Expand All@@ -2046,13 +2056,45 @@
 SAnnPush _ s -> go s
 SAnnPop s -> go s

plainLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
plainLine i x = SLine i x

smartLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
smartLine i x =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x

-- | Remove indentation that would otherwise survive on empty lines.
dropIndentationOnEmptyLines :: SimpleDocStream ann -> SimpleDocStream ann
dropIndentationOnEmptyLines = go
 where
 go sds = case sds of
 SFail -> SFail
 SEmpty -> SEmpty
 SChar c x -> SChar c (go x)
 SText l t x -> SText l t (go x)
 SLine i x ->
 let x' = go x
 i' = case x' of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x'
 SAnnPush ann x -> SAnnPush ann (go x)
 SAnnPop x -> SAnnPop (go x)

-- | The Wadler/Leijen layout algorithm
layoutWadlerLeijen
 :: forall ann. FittingPredicate ann
 :: forall ann. (Int -> SimpleDocStream ann -> SimpleDocStream ann)
 -> FittingPredicate ann
 -> PageWidth
 -> Doc ann
 -> SimpleDocStream ann
layoutWadlerLeijen
 mkLine
 (FittingPredicate fits)
 pageWidth_
 doc
Expand All@@ -2073,15 +2115,7 @@
 Empty -> best nl cc ds
 Char c -> let !cc' = cc+1 in SChar c (best nl cc' ds)
 Text l t -> let !cc' = cc+l in SText l t (best nl cc' ds)
 Line -> let x = best i i ds
 -- Don't produce indentation if there's no
 -- following text on the same line.
 -- This prevents trailing whitespace.
 i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x
 Line -> mkLine i (best i i ds)
 FlatAlt x _ -> best nl cc (Cons i x ds)
 Cat x y -> best nl cc (Cons i x (Cons i y ds))
 Nest j x -> let !ij = i+j in best nl cc (Cons ij x ds)
Expand Down

10 changes: 10 additions & 0 deletions
prettyprinter/test/Testsuite/Main.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -53,6 +53,8 @@ tests = testGroup "Tests"
 groupingPerformance
 , testCase "fillSep performance"
 fillSepPerformance
 , testCase "Issue 205"
 issue205
 ]
 , testGroup "Regression tests"
 [ testCase "layoutSmart: softline behaves like a newline (#49)"
Expand DownExpand Up@@ -285,6 +287,14 @@ fillSepPerformance = docPerformanceTest (pathological 1000)
 pathological :: Int -> Doc ann
 pathological n = iterate (\x -> fillSep ["a", x <+> "b"] ) "foobar" !! n

issue205 :: Assertion
issue205 = do
 let doc = fillSep (replicate 30 (sep ["abc", "xyz" :: Doc ()]))
 t = renderStrict (layoutSmart defaultLayoutOptions doc)
 timeout 1000000 (evaluate t) >>= \t' -> case t' of
 Nothing -> assertFailure "Timeout!"
 Just _success -> pure ()

regressionLayoutSmartSoftline :: Assertion
regressionLayoutSmartSoftline
 = let doc = "a" <> softline <> "b"
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
.markdown-body hr { border-color: #30363d; }
';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Alternative fix for #205 by sjakobi · Pull Request #283 · haskell-prettyprinter/prettyprinter · GitHub
Skip to content
Alternative fix for #205#283

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Sign in
to your account

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commits into

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Alternative fix for #205
#283
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a5342e4

Add performance test for #205


sjakobi Dec 5, 2025
c584f60

Fix layoutSmart regression from blank-line indentation


sjakobi Mar 30, 2026

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58 changes: 46 additions & 12 deletions
prettyprinter/src/Prettyprinter/Internal.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1895,6 +1895,7 @@
 -> SimpleDocStream ann
layoutPretty (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\lineIndent currentColumn _initialIndentY sdoc ->
 fits
Expand DownExpand Up@@ -1982,7 +1983,8 @@
 -> Doc ann
 -> SimpleDocStream ann
layoutSmart (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen (FittingPredicate fits) pageWidth_
 dropIndentationOnEmptyLines .
 layoutWadlerLeijen plainLine (FittingPredicate fits) pageWidth_
 where
 -- Why doesn't layoutSmart simply check the entire document?
 --
Expand All@@ -2001,7 +2003,14 @@
 go w (SChar _ x) = go (w - 1) x
 go w (SText l _t x) = go (w - l) x
 go _ (SLine i x)
 | minNestingLevel < i = go (lineLength - i) x -- TODO: Take ribbon width into account?! (#142)
 | minNestingLevel < i =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in if minNestingLevel < i'

Check warning
on line 2011
in prettyprinter/src/Prettyprinter/Internal.hs

View workflow job for this annotation
GitHub Actions/ hlint
Warning in layoutSmart in module Prettyprinter.Internal: Redundant if ▫︎ Found: "if minNestingLevel < i' then go (lineLength - i') x else True" ▫︎ Perhaps: "(not (minNestingLevel < i') || go (lineLength - i') x)"
 then go (lineLength - i') x -- TODO: Take ribbon width into account?! (#142)
 else True
 | otherwise = True
 go w (SAnnPush _ x) = go w x
 go w (SAnnPop x) = go w x
Expand DownExpand Up@@ -2029,6 +2038,7 @@
layoutUnbounded :: Doc ann -> SimpleDocStream ann
layoutUnbounded =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\_lineIndent _currentColumn _initialIndentY sdoc -> not (failsOnFirstLine sdoc)))
 Unbounded
Expand All@@ -2046,13 +2056,45 @@
 SAnnPush _ s -> go s
 SAnnPop s -> go s

plainLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
plainLine i x = SLine i x

smartLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
smartLine i x =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x

-- | Remove indentation that would otherwise survive on empty lines.
dropIndentationOnEmptyLines :: SimpleDocStream ann -> SimpleDocStream ann
dropIndentationOnEmptyLines = go
 where
 go sds = case sds of
 SFail -> SFail
 SEmpty -> SEmpty
 SChar c x -> SChar c (go x)
 SText l t x -> SText l t (go x)
 SLine i x ->
 let x' = go x
 i' = case x' of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x'
 SAnnPush ann x -> SAnnPush ann (go x)
 SAnnPop x -> SAnnPop (go x)

-- | The Wadler/Leijen layout algorithm
layoutWadlerLeijen
 :: forall ann. FittingPredicate ann
 :: forall ann. (Int -> SimpleDocStream ann -> SimpleDocStream ann)
 -> FittingPredicate ann
 -> PageWidth
 -> Doc ann
 -> SimpleDocStream ann
layoutWadlerLeijen
 mkLine
 (FittingPredicate fits)
 pageWidth_
 doc
Expand All@@ -2073,15 +2115,7 @@
 Empty -> best nl cc ds
 Char c -> let !cc' = cc+1 in SChar c (best nl cc' ds)
 Text l t -> let !cc' = cc+l in SText l t (best nl cc' ds)
 Line -> let x = best i i ds
 -- Don't produce indentation if there's no
 -- following text on the same line.
 -- This prevents trailing whitespace.
 i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x
 Line -> mkLine i (best i i ds)
 FlatAlt x _ -> best nl cc (Cons i x ds)
 Cat x y -> best nl cc (Cons i x (Cons i y ds))
 Nest j x -> let !ij = i+j in best nl cc (Cons ij x ds)
Expand Down

10 changes: 10 additions & 0 deletions
prettyprinter/test/Testsuite/Main.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -53,6 +53,8 @@ tests = testGroup "Tests"
 groupingPerformance
 , testCase "fillSep performance"
 fillSepPerformance
 , testCase "Issue 205"
 issue205
 ]
 , testGroup "Regression tests"
 [ testCase "layoutSmart: softline behaves like a newline (#49)"
Expand DownExpand Up@@ -285,6 +287,14 @@ fillSepPerformance = docPerformanceTest (pathological 1000)
 pathological :: Int -> Doc ann
 pathological n = iterate (\x -> fillSep ["a", x <+> "b"] ) "foobar" !! n

issue205 :: Assertion
issue205 = do
 let doc = fillSep (replicate 30 (sep ["abc", "xyz" :: Doc ()]))
 t = renderStrict (layoutSmart defaultLayoutOptions doc)
 timeout 1000000 (evaluate t) >>= \t' -> case t' of
 Nothing -> assertFailure "Timeout!"
 Just _success -> pure ()

regressionLayoutSmartSoftline :: Assertion
regressionLayoutSmartSoftline
 = let doc = "a" <> softline <> "b"
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Alternative fix for #205 by sjakobi · Pull Request #283 · haskell-prettyprinter/prettyprinter · GitHub
Skip to content
Alternative fix for #205#283

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Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

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privacy statement. We’ll occasionally send you account related emails.

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to your account

 Draft

sjakobi
wants to merge
2
commits into

base:master
Choose a base branch

from

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Alternative fix for #205
#283
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a5342e4

Add performance test for #205


sjakobi Dec 5, 2025
c584f60

Fix layoutSmart regression from blank-line indentation


sjakobi Mar 30, 2026

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58 changes: 46 additions & 12 deletions
prettyprinter/src/Prettyprinter/Internal.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1895,6 +1895,7 @@
 -> SimpleDocStream ann
layoutPretty (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\lineIndent currentColumn _initialIndentY sdoc ->
 fits
Expand DownExpand Up@@ -1982,7 +1983,8 @@
 -> Doc ann
 -> SimpleDocStream ann
layoutSmart (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen (FittingPredicate fits) pageWidth_
 dropIndentationOnEmptyLines .
 layoutWadlerLeijen plainLine (FittingPredicate fits) pageWidth_
 where
 -- Why doesn't layoutSmart simply check the entire document?
 --
Expand All@@ -2001,7 +2003,14 @@
 go w (SChar _ x) = go (w - 1) x
 go w (SText l _t x) = go (w - l) x
 go _ (SLine i x)
 | minNestingLevel < i = go (lineLength - i) x -- TODO: Take ribbon width into account?! (#142)
 | minNestingLevel < i =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in if minNestingLevel < i'

Check warning
on line 2011
in prettyprinter/src/Prettyprinter/Internal.hs

View workflow job for this annotation
GitHub Actions/ hlint
Warning in layoutSmart in module Prettyprinter.Internal: Redundant if ▫︎ Found: "if minNestingLevel < i' then go (lineLength - i') x else True" ▫︎ Perhaps: "(not (minNestingLevel < i') || go (lineLength - i') x)"
 then go (lineLength - i') x -- TODO: Take ribbon width into account?! (#142)
 else True
 | otherwise = True
 go w (SAnnPush _ x) = go w x
 go w (SAnnPop x) = go w x
Expand DownExpand Up@@ -2029,6 +2038,7 @@
layoutUnbounded :: Doc ann -> SimpleDocStream ann
layoutUnbounded =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\_lineIndent _currentColumn _initialIndentY sdoc -> not (failsOnFirstLine sdoc)))
 Unbounded
Expand All@@ -2046,13 +2056,45 @@
 SAnnPush _ s -> go s
 SAnnPop s -> go s

plainLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
plainLine i x = SLine i x

smartLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
smartLine i x =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x

-- | Remove indentation that would otherwise survive on empty lines.
dropIndentationOnEmptyLines :: SimpleDocStream ann -> SimpleDocStream ann
dropIndentationOnEmptyLines = go
 where
 go sds = case sds of
 SFail -> SFail
 SEmpty -> SEmpty
 SChar c x -> SChar c (go x)
 SText l t x -> SText l t (go x)
 SLine i x ->
 let x' = go x
 i' = case x' of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x'
 SAnnPush ann x -> SAnnPush ann (go x)
 SAnnPop x -> SAnnPop (go x)

-- | The Wadler/Leijen layout algorithm
layoutWadlerLeijen
 :: forall ann. FittingPredicate ann
 :: forall ann. (Int -> SimpleDocStream ann -> SimpleDocStream ann)
 -> FittingPredicate ann
 -> PageWidth
 -> Doc ann
 -> SimpleDocStream ann
layoutWadlerLeijen
 mkLine
 (FittingPredicate fits)
 pageWidth_
 doc
Expand All@@ -2073,15 +2115,7 @@
 Empty -> best nl cc ds
 Char c -> let !cc' = cc+1 in SChar c (best nl cc' ds)
 Text l t -> let !cc' = cc+l in SText l t (best nl cc' ds)
 Line -> let x = best i i ds
 -- Don't produce indentation if there's no
 -- following text on the same line.
 -- This prevents trailing whitespace.
 i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x
 Line -> mkLine i (best i i ds)
 FlatAlt x _ -> best nl cc (Cons i x ds)
 Cat x y -> best nl cc (Cons i x (Cons i y ds))
 Nest j x -> let !ij = i+j in best nl cc (Cons ij x ds)
Expand Down

10 changes: 10 additions & 0 deletions
prettyprinter/test/Testsuite/Main.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -53,6 +53,8 @@ tests = testGroup "Tests"
 groupingPerformance
 , testCase "fillSep performance"
 fillSepPerformance
 , testCase "Issue 205"
 issue205
 ]
 , testGroup "Regression tests"
 [ testCase "layoutSmart: softline behaves like a newline (#49)"
Expand DownExpand Up@@ -285,6 +287,14 @@ fillSepPerformance = docPerformanceTest (pathological 1000)
 pathological :: Int -> Doc ann
 pathological n = iterate (\x -> fillSep ["a", x <+> "b"] ) "foobar" !! n

issue205 :: Assertion
issue205 = do
 let doc = fillSep (replicate 30 (sep ["abc", "xyz" :: Doc ()]))
 t = renderStrict (layoutSmart defaultLayoutOptions doc)
 timeout 1000000 (evaluate t) >>= \t' -> case t' of
 Nothing -> assertFailure "Timeout!"
 Just _success -> pure ()

regressionLayoutSmartSoftline :: Assertion
regressionLayoutSmartSoftline
 = let doc = "a" <> softline <> "b"
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Alternative fix for #205 by sjakobi · Pull Request #283 · haskell-prettyprinter/prettyprinter · GitHub
Skip to content
Alternative fix for #205#283

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#283
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a5342e4

Add performance test for #205


sjakobi Dec 5, 2025
c584f60

Fix layoutSmart regression from blank-line indentation


sjakobi Mar 30, 2026

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58 changes: 46 additions & 12 deletions
prettyprinter/src/Prettyprinter/Internal.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1895,6 +1895,7 @@
 -> SimpleDocStream ann
layoutPretty (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\lineIndent currentColumn _initialIndentY sdoc ->
 fits
Expand DownExpand Up@@ -1982,7 +1983,8 @@
 -> Doc ann
 -> SimpleDocStream ann
layoutSmart (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen (FittingPredicate fits) pageWidth_
 dropIndentationOnEmptyLines .
 layoutWadlerLeijen plainLine (FittingPredicate fits) pageWidth_
 where
 -- Why doesn't layoutSmart simply check the entire document?
 --
Expand All@@ -2001,7 +2003,14 @@
 go w (SChar _ x) = go (w - 1) x
 go w (SText l _t x) = go (w - l) x
 go _ (SLine i x)
 | minNestingLevel < i = go (lineLength - i) x -- TODO: Take ribbon width into account?! (#142)
 | minNestingLevel < i =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in if minNestingLevel < i'

Check warning
on line 2011
in prettyprinter/src/Prettyprinter/Internal.hs

View workflow job for this annotation
GitHub Actions/ hlint
Warning in layoutSmart in module Prettyprinter.Internal: Redundant if ▫︎ Found: "if minNestingLevel < i' then go (lineLength - i') x else True" ▫︎ Perhaps: "(not (minNestingLevel < i') || go (lineLength - i') x)"
 then go (lineLength - i') x -- TODO: Take ribbon width into account?! (#142)
 else True
 | otherwise = True
 go w (SAnnPush _ x) = go w x
 go w (SAnnPop x) = go w x
Expand DownExpand Up@@ -2029,6 +2038,7 @@
layoutUnbounded :: Doc ann -> SimpleDocStream ann
layoutUnbounded =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\_lineIndent _currentColumn _initialIndentY sdoc -> not (failsOnFirstLine sdoc)))
 Unbounded
Expand All@@ -2046,13 +2056,45 @@
 SAnnPush _ s -> go s
 SAnnPop s -> go s

plainLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
plainLine i x = SLine i x

smartLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
smartLine i x =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x

-- | Remove indentation that would otherwise survive on empty lines.
dropIndentationOnEmptyLines :: SimpleDocStream ann -> SimpleDocStream ann
dropIndentationOnEmptyLines = go
 where
 go sds = case sds of
 SFail -> SFail
 SEmpty -> SEmpty
 SChar c x -> SChar c (go x)
 SText l t x -> SText l t (go x)
 SLine i x ->
 let x' = go x
 i' = case x' of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x'
 SAnnPush ann x -> SAnnPush ann (go x)
 SAnnPop x -> SAnnPop (go x)

-- | The Wadler/Leijen layout algorithm
layoutWadlerLeijen
 :: forall ann. FittingPredicate ann
 :: forall ann. (Int -> SimpleDocStream ann -> SimpleDocStream ann)
 -> FittingPredicate ann
 -> PageWidth
 -> Doc ann
 -> SimpleDocStream ann
layoutWadlerLeijen
 mkLine
 (FittingPredicate fits)
 pageWidth_
 doc
Expand All@@ -2073,15 +2115,7 @@
 Empty -> best nl cc ds
 Char c -> let !cc' = cc+1 in SChar c (best nl cc' ds)
 Text l t -> let !cc' = cc+l in SText l t (best nl cc' ds)
 Line -> let x = best i i ds
 -- Don't produce indentation if there's no
 -- following text on the same line.
 -- This prevents trailing whitespace.
 i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x
 Line -> mkLine i (best i i ds)
 FlatAlt x _ -> best nl cc (Cons i x ds)
 Cat x y -> best nl cc (Cons i x (Cons i y ds))
 Nest j x -> let !ij = i+j in best nl cc (Cons ij x ds)
Expand Down

10 changes: 10 additions & 0 deletions
prettyprinter/test/Testsuite/Main.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -53,6 +53,8 @@ tests = testGroup "Tests"
 groupingPerformance
 , testCase "fillSep performance"
 fillSepPerformance
 , testCase "Issue 205"
 issue205
 ]
 , testGroup "Regression tests"
 [ testCase "layoutSmart: softline behaves like a newline (#49)"
Expand DownExpand Up@@ -285,6 +287,14 @@ fillSepPerformance = docPerformanceTest (pathological 1000)
 pathological :: Int -> Doc ann
 pathological n = iterate (\x -> fillSep ["a", x <+> "b"] ) "foobar" !! n

issue205 :: Assertion
issue205 = do
 let doc = fillSep (replicate 30 (sep ["abc", "xyz" :: Doc ()]))
 t = renderStrict (layoutSmart defaultLayoutOptions doc)
 timeout 1000000 (evaluate t) >>= \t' -> case t' of
 Nothing -> assertFailure "Timeout!"
 Just _success -> pure ()

regressionLayoutSmartSoftline :: Assertion
regressionLayoutSmartSoftline
 = let doc = "a" <> softline <> "b"
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Alternative fix for #205 by sjakobi · Pull Request #283 · haskell-prettyprinter/prettyprinter · GitHub
Skip to content
Alternative fix for #205#283

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to your account

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commits into

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Alternative fix for #205
#283
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a5342e4

Add performance test for #205


sjakobi Dec 5, 2025
c584f60

Fix layoutSmart regression from blank-line indentation


sjakobi Mar 30, 2026

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58 changes: 46 additions & 12 deletions
prettyprinter/src/Prettyprinter/Internal.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1895,6 +1895,7 @@
 -> SimpleDocStream ann
layoutPretty (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\lineIndent currentColumn _initialIndentY sdoc ->
 fits
Expand DownExpand Up@@ -1982,7 +1983,8 @@
 -> Doc ann
 -> SimpleDocStream ann
layoutSmart (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen (FittingPredicate fits) pageWidth_
 dropIndentationOnEmptyLines .
 layoutWadlerLeijen plainLine (FittingPredicate fits) pageWidth_
 where
 -- Why doesn't layoutSmart simply check the entire document?
 --
Expand All@@ -2001,7 +2003,14 @@
 go w (SChar _ x) = go (w - 1) x
 go w (SText l _t x) = go (w - l) x
 go _ (SLine i x)
 | minNestingLevel < i = go (lineLength - i) x -- TODO: Take ribbon width into account?! (#142)
 | minNestingLevel < i =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in if minNestingLevel < i'

Check warning
on line 2011
in prettyprinter/src/Prettyprinter/Internal.hs

View workflow job for this annotation
GitHub Actions/ hlint
Warning in layoutSmart in module Prettyprinter.Internal: Redundant if ▫︎ Found: "if minNestingLevel < i' then go (lineLength - i') x else True" ▫︎ Perhaps: "(not (minNestingLevel < i') || go (lineLength - i') x)"
 then go (lineLength - i') x -- TODO: Take ribbon width into account?! (#142)
 else True
 | otherwise = True
 go w (SAnnPush _ x) = go w x
 go w (SAnnPop x) = go w x
Expand DownExpand Up@@ -2029,6 +2038,7 @@
layoutUnbounded :: Doc ann -> SimpleDocStream ann
layoutUnbounded =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\_lineIndent _currentColumn _initialIndentY sdoc -> not (failsOnFirstLine sdoc)))
 Unbounded
Expand All@@ -2046,13 +2056,45 @@
 SAnnPush _ s -> go s
 SAnnPop s -> go s

plainLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
plainLine i x = SLine i x

smartLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
smartLine i x =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x

-- | Remove indentation that would otherwise survive on empty lines.
dropIndentationOnEmptyLines :: SimpleDocStream ann -> SimpleDocStream ann
dropIndentationOnEmptyLines = go
 where
 go sds = case sds of
 SFail -> SFail
 SEmpty -> SEmpty
 SChar c x -> SChar c (go x)
 SText l t x -> SText l t (go x)
 SLine i x ->
 let x' = go x
 i' = case x' of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x'
 SAnnPush ann x -> SAnnPush ann (go x)
 SAnnPop x -> SAnnPop (go x)

-- | The Wadler/Leijen layout algorithm
layoutWadlerLeijen
 :: forall ann. FittingPredicate ann
 :: forall ann. (Int -> SimpleDocStream ann -> SimpleDocStream ann)
 -> FittingPredicate ann
 -> PageWidth
 -> Doc ann
 -> SimpleDocStream ann
layoutWadlerLeijen
 mkLine
 (FittingPredicate fits)
 pageWidth_
 doc
Expand All@@ -2073,15 +2115,7 @@
 Empty -> best nl cc ds
 Char c -> let !cc' = cc+1 in SChar c (best nl cc' ds)
 Text l t -> let !cc' = cc+l in SText l t (best nl cc' ds)
 Line -> let x = best i i ds
 -- Don't produce indentation if there's no
 -- following text on the same line.
 -- This prevents trailing whitespace.
 i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x
 Line -> mkLine i (best i i ds)
 FlatAlt x _ -> best nl cc (Cons i x ds)
 Cat x y -> best nl cc (Cons i x (Cons i y ds))
 Nest j x -> let !ij = i+j in best nl cc (Cons ij x ds)
Expand Down

10 changes: 10 additions & 0 deletions
prettyprinter/test/Testsuite/Main.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -53,6 +53,8 @@ tests = testGroup "Tests"
 groupingPerformance
 , testCase "fillSep performance"
 fillSepPerformance
 , testCase "Issue 205"
 issue205
 ]
 , testGroup "Regression tests"
 [ testCase "layoutSmart: softline behaves like a newline (#49)"
Expand DownExpand Up@@ -285,6 +287,14 @@ fillSepPerformance = docPerformanceTest (pathological 1000)
 pathological :: Int -> Doc ann
 pathological n = iterate (\x -> fillSep ["a", x <+> "b"] ) "foobar" !! n

issue205 :: Assertion
issue205 = do
 let doc = fillSep (replicate 30 (sep ["abc", "xyz" :: Doc ()]))
 t = renderStrict (layoutSmart defaultLayoutOptions doc)
 timeout 1000000 (evaluate t) >>= \t' -> case t' of
 Nothing -> assertFailure "Timeout!"
 Just _success -> pure ()

regressionLayoutSmartSoftline :: Assertion
regressionLayoutSmartSoftline
 = let doc = "a" <> softline <> "b"
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Alternative fix for #205 by sjakobi · Pull Request #283 · haskell-prettyprinter/prettyprinter · GitHub
Skip to content
Alternative fix for #205#283

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

 Sign up for GitHub

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privacy statement. We’ll occasionally send you account related emails.

Already on GitHub?
Sign in
to your account

 Draft

sjakobi
wants to merge
2
commits into

base:master
Choose a base branch

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Alternative fix for #205
#283
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a5342e4

Add performance test for #205


sjakobi Dec 5, 2025
c584f60

Fix layoutSmart regression from blank-line indentation


sjakobi Mar 30, 2026

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58 changes: 46 additions & 12 deletions
prettyprinter/src/Prettyprinter/Internal.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1895,6 +1895,7 @@
 -> SimpleDocStream ann
layoutPretty (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\lineIndent currentColumn _initialIndentY sdoc ->
 fits
Expand DownExpand Up@@ -1982,7 +1983,8 @@
 -> Doc ann
 -> SimpleDocStream ann
layoutSmart (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen (FittingPredicate fits) pageWidth_
 dropIndentationOnEmptyLines .
 layoutWadlerLeijen plainLine (FittingPredicate fits) pageWidth_
 where
 -- Why doesn't layoutSmart simply check the entire document?
 --
Expand All@@ -2001,7 +2003,14 @@
 go w (SChar _ x) = go (w - 1) x
 go w (SText l _t x) = go (w - l) x
 go _ (SLine i x)
 | minNestingLevel < i = go (lineLength - i) x -- TODO: Take ribbon width into account?! (#142)
 | minNestingLevel < i =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in if minNestingLevel < i'

Check warning
on line 2011
in prettyprinter/src/Prettyprinter/Internal.hs

View workflow job for this annotation
GitHub Actions/ hlint
Warning in layoutSmart in module Prettyprinter.Internal: Redundant if ▫︎ Found: "if minNestingLevel < i' then go (lineLength - i') x else True" ▫︎ Perhaps: "(not (minNestingLevel < i') || go (lineLength - i') x)"
 then go (lineLength - i') x -- TODO: Take ribbon width into account?! (#142)
 else True
 | otherwise = True
 go w (SAnnPush _ x) = go w x
 go w (SAnnPop x) = go w x
Expand DownExpand Up@@ -2029,6 +2038,7 @@
layoutUnbounded :: Doc ann -> SimpleDocStream ann
layoutUnbounded =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\_lineIndent _currentColumn _initialIndentY sdoc -> not (failsOnFirstLine sdoc)))
 Unbounded
Expand All@@ -2046,13 +2056,45 @@
 SAnnPush _ s -> go s
 SAnnPop s -> go s

plainLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
plainLine i x = SLine i x

smartLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
smartLine i x =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x

-- | Remove indentation that would otherwise survive on empty lines.
dropIndentationOnEmptyLines :: SimpleDocStream ann -> SimpleDocStream ann
dropIndentationOnEmptyLines = go
 where
 go sds = case sds of
 SFail -> SFail
 SEmpty -> SEmpty
 SChar c x -> SChar c (go x)
 SText l t x -> SText l t (go x)
 SLine i x ->
 let x' = go x
 i' = case x' of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x'
 SAnnPush ann x -> SAnnPush ann (go x)
 SAnnPop x -> SAnnPop (go x)

-- | The Wadler/Leijen layout algorithm
layoutWadlerLeijen
 :: forall ann. FittingPredicate ann
 :: forall ann. (Int -> SimpleDocStream ann -> SimpleDocStream ann)
 -> FittingPredicate ann
 -> PageWidth
 -> Doc ann
 -> SimpleDocStream ann
layoutWadlerLeijen
 mkLine
 (FittingPredicate fits)
 pageWidth_
 doc
Expand All@@ -2073,15 +2115,7 @@
 Empty -> best nl cc ds
 Char c -> let !cc' = cc+1 in SChar c (best nl cc' ds)
 Text l t -> let !cc' = cc+l in SText l t (best nl cc' ds)
 Line -> let x = best i i ds
 -- Don't produce indentation if there's no
 -- following text on the same line.
 -- This prevents trailing whitespace.
 i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x
 Line -> mkLine i (best i i ds)
 FlatAlt x _ -> best nl cc (Cons i x ds)
 Cat x y -> best nl cc (Cons i x (Cons i y ds))
 Nest j x -> let !ij = i+j in best nl cc (Cons ij x ds)
Expand Down

10 changes: 10 additions & 0 deletions
prettyprinter/test/Testsuite/Main.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -53,6 +53,8 @@ tests = testGroup "Tests"
 groupingPerformance
 , testCase "fillSep performance"
 fillSepPerformance
 , testCase "Issue 205"
 issue205
 ]
 , testGroup "Regression tests"
 [ testCase "layoutSmart: softline behaves like a newline (#49)"
Expand DownExpand Up@@ -285,6 +287,14 @@ fillSepPerformance = docPerformanceTest (pathological 1000)
 pathological :: Int -> Doc ann
 pathological n = iterate (\x -> fillSep ["a", x <+> "b"] ) "foobar" !! n

issue205 :: Assertion
issue205 = do
 let doc = fillSep (replicate 30 (sep ["abc", "xyz" :: Doc ()]))
 t = renderStrict (layoutSmart defaultLayoutOptions doc)
 timeout 1000000 (evaluate t) >>= \t' -> case t' of
 Nothing -> assertFailure "Timeout!"
 Just _success -> pure ()

regressionLayoutSmartSoftline :: Assertion
regressionLayoutSmartSoftline
 = let doc = "a" <> softline <> "b"
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
Alternative fix for #205 by sjakobi · Pull Request #283 · haskell-prettyprinter/prettyprinter · GitHub
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Alternative fix for #205
#283
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a5342e4

Add performance test for #205


sjakobi Dec 5, 2025
c584f60

Fix layoutSmart regression from blank-line indentation


sjakobi Mar 30, 2026

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58 changes: 46 additions & 12 deletions
prettyprinter/src/Prettyprinter/Internal.hs

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -1895,6 +1895,7 @@
 -> SimpleDocStream ann
layoutPretty (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\lineIndent currentColumn _initialIndentY sdoc ->
 fits
Expand DownExpand Up@@ -1982,7 +1983,8 @@
 -> Doc ann
 -> SimpleDocStream ann
layoutSmart (LayoutOptions pageWidth_@(AvailablePerLine lineLength ribbonFraction)) =
 layoutWadlerLeijen (FittingPredicate fits) pageWidth_
 dropIndentationOnEmptyLines .
 layoutWadlerLeijen plainLine (FittingPredicate fits) pageWidth_
 where
 -- Why doesn't layoutSmart simply check the entire document?
 --
Expand All@@ -2001,7 +2003,14 @@
 go w (SChar _ x) = go (w - 1) x
 go w (SText l _t x) = go (w - l) x
 go _ (SLine i x)
 | minNestingLevel < i = go (lineLength - i) x -- TODO: Take ribbon width into account?! (#142)
 | minNestingLevel < i =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in if minNestingLevel < i'

Check warning
on line 2011
in prettyprinter/src/Prettyprinter/Internal.hs

View workflow job for this annotation
GitHub Actions/ hlint
Warning in layoutSmart in module Prettyprinter.Internal: Redundant if ▫︎ Found: "if minNestingLevel < i' then go (lineLength - i') x else True" ▫︎ Perhaps: "(not (minNestingLevel < i') || go (lineLength - i') x)"
 then go (lineLength - i') x -- TODO: Take ribbon width into account?! (#142)
 else True
 | otherwise = True
 go w (SAnnPush _ x) = go w x
 go w (SAnnPop x) = go w x
Expand DownExpand Up@@ -2029,6 +2038,7 @@
layoutUnbounded :: Doc ann -> SimpleDocStream ann
layoutUnbounded =
 layoutWadlerLeijen
 smartLine
 (FittingPredicate
 (\_lineIndent _currentColumn _initialIndentY sdoc -> not (failsOnFirstLine sdoc)))
 Unbounded
Expand All@@ -2046,13 +2056,45 @@
 SAnnPush _ s -> go s
 SAnnPop s -> go s

plainLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
plainLine i x = SLine i x

smartLine :: Int -> SimpleDocStream ann -> SimpleDocStream ann
smartLine i x =
 let i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x

-- | Remove indentation that would otherwise survive on empty lines.
dropIndentationOnEmptyLines :: SimpleDocStream ann -> SimpleDocStream ann
dropIndentationOnEmptyLines = go
 where
 go sds = case sds of
 SFail -> SFail
 SEmpty -> SEmpty
 SChar c x -> SChar c (go x)
 SText l t x -> SText l t (go x)
 SLine i x ->
 let x' = go x
 i' = case x' of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x'
 SAnnPush ann x -> SAnnPush ann (go x)
 SAnnPop x -> SAnnPop (go x)

-- | The Wadler/Leijen layout algorithm
layoutWadlerLeijen
 :: forall ann. FittingPredicate ann
 :: forall ann. (Int -> SimpleDocStream ann -> SimpleDocStream ann)
 -> FittingPredicate ann
 -> PageWidth
 -> Doc ann
 -> SimpleDocStream ann
layoutWadlerLeijen
 mkLine
 (FittingPredicate fits)
 pageWidth_
 doc
Expand All@@ -2073,15 +2115,7 @@
 Empty -> best nl cc ds
 Char c -> let !cc' = cc+1 in SChar c (best nl cc' ds)
 Text l t -> let !cc' = cc+l in SText l t (best nl cc' ds)
 Line -> let x = best i i ds
 -- Don't produce indentation if there's no
 -- following text on the same line.
 -- This prevents trailing whitespace.
 i' = case x of
 SEmpty -> 0
 SLine{} -> 0
 _ -> i
 in SLine i' x
 Line -> mkLine i (best i i ds)
 FlatAlt x _ -> best nl cc (Cons i x ds)
 Cat x y -> best nl cc (Cons i x (Cons i y ds))
 Nest j x -> let !ij = i+j in best nl cc (Cons ij x ds)
Expand Down

10 changes: 10 additions & 0 deletions
prettyprinter/test/Testsuite/Main.hs

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -53,6 +53,8 @@ tests = testGroup "Tests"
 groupingPerformance
 , testCase "fillSep performance"
 fillSepPerformance
 , testCase "Issue 205"
 issue205
 ]
 , testGroup "Regression tests"
 [ testCase "layoutSmart: softline behaves like a newline (#49)"
Expand DownExpand Up@@ -285,6 +287,14 @@ fillSepPerformance = docPerformanceTest (pathological 1000)
 pathological :: Int -> Doc ann
 pathological n = iterate (\x -> fillSep ["a", x <+> "b"] ) "foobar" !! n

issue205 :: Assertion
issue205 = do
 let doc = fillSep (replicate 30 (sep ["abc", "xyz" :: Doc ()]))
 t = renderStrict (layoutSmart defaultLayoutOptions doc)
 timeout 1000000 (evaluate t) >>= \t' -> case t' of
 Nothing -> assertFailure "Timeout!"
 Just _success -> pure ()

regressionLayoutSmartSoftline :: Assertion
regressionLayoutSmartSoftline
 = let doc = "a" <> softline <> "b"
Expand Down
Loading