diff --git a/prettyprinter/src/Prettyprinter/Internal.hs b/prettyprinter/src/Prettyprinter/Internal.hs
index ca4c0b10..32747c97 100755
--- a/prettyprinter/src/Prettyprinter/Internal.hs
+++ b/prettyprinter/src/Prettyprinter/Internal.hs
@@ -976,7 +976,7 @@ concatWith f ds
 -- lorem ipsum dolor sit amet
 --
 -- For automatic line breaks, consider using 'fillSep' instead.
-hsep :: [Doc ann] -> Doc ann
+hsep :: Foldable f => f (Doc ann) -> Doc ann
 hsep = concatWith (<+>)
 
 -- | @('vsep' xs)@ concatenates all documents @xs@ above each other. If a
@@ -1006,7 +1006,7 @@ hsep = concatWith (<+>)
 --
 -- Since 'group'ing a 'vsep' is rather common, 'sep' is a built-in for doing
 -- that.
-vsep :: [Doc ann] -> Doc ann
+vsep :: Foldable f => f (Doc ann) -> Doc ann
 vsep = concatWith (\x y -> x <> line <> y)
 
 -- | @('fillSep' xs)@ concatenates the documents @xs@ horizontally with @'<+>'@
@@ -1028,7 +1028,7 @@ vsep = concatWith (\x y -> x <> line <> y)
 -- Docs: lorem ipsum dolor sit amet lorem
 -- ipsum dolor sit amet lorem ipsum dolor
 -- sit amet lorem ipsum dolor sit amet
-fillSep :: [Doc ann] -> Doc ann
+fillSep :: Foldable f => f (Doc ann) -> Doc ann
 fillSep = concatWith (\x y -> x <> softline <> y)
 
 -- | @('sep' xs)@ tries laying out the documents @xs@ separated with 'space's,
@@ -1051,7 +1051,7 @@ fillSep = concatWith (\x y -> x <> softline <> y)
 -- @
 -- 'sep' = 'group' . 'vsep'
 -- @
-sep :: [Doc ann] -> Doc ann
+sep :: Foldable f => f (Doc ann) -> Doc ann
 sep = group . vsep
 
 
@@ -1064,7 +1064,7 @@ sep = group . vsep
 -- >>> let docs = Util.words "lorem ipsum dolor"
 -- >>> hcat docs
 -- loremipsumdolor
-hcat :: [Doc ann] -> Doc ann
+hcat :: Foldable f => f (Doc ann) -> Doc ann
 hcat = concatWith (<>)
 
 -- | @('vcat' xs)@ vertically concatenates the documents @xs@. If it is
@@ -1083,7 +1083,7 @@ hcat = concatWith (<>)
 --
 -- Since 'group'ing a 'vcat' is rather common, 'cat' is a built-in shortcut for
 -- it.
-vcat :: [Doc ann] -> Doc ann
+vcat :: Foldable f => f (Doc ann) -> Doc ann
 vcat = concatWith (\x y -> x <> line' <> y)
 
 -- | @('fillCat' xs)@ concatenates documents @xs@ horizontally with @'<>'@ as
@@ -1112,7 +1112,7 @@ vcat = concatWith (\x y -> x <> line' <> y)
 -- Grouped: loremipsumdolorsitametlorem
 -- ipsumdolorsitametloremipsumdolorsitamet
 -- loremipsumdolorsitamet
-fillCat :: [Doc ann] -> Doc ann
+fillCat :: Foldable f => f (Doc ann) -> Doc ann
 fillCat = concatWith (\x y -> x <> softline' <> y)
 
 -- | @('cat' xs)@ tries laying out the documents @xs@ separated with nothing,
@@ -1134,7 +1134,7 @@ fillCat = concatWith (\x y -> x <> softline' <> y)
 -- @
 -- 'cat' = 'group' . 'vcat'
 -- @
-cat :: [Doc ann] -> Doc ann
+cat :: Foldable f => f (Doc ann) -> Doc ann
 cat = group . vcat
 
 
@@ -1806,8 +1806,8 @@ defaultLayoutOptions = LayoutOptions { layoutPageWidth = defaultPageWidth }
 -- | This is the default layout algorithm, and it is used by 'show', 'putDoc'
 -- and 'hPutDoc'.
 --
--- @'layoutPretty'@ commits to rendering something in a certain way if the 
--- remainder of the current line fits the layout constraints; in other words, 
+-- @'layoutPretty'@ commits to rendering something in a certain way if the
+-- remainder of the current line fits the layout constraints; in other words,
 -- it has up to one line of lookahead when rendering. Consider using the
 -- smarter, but a bit less performant, @'layoutSmart'@ algorithm if the results
 -- seem to run off to the right before having lots of line breaks.