{-# LANGUAGE QuasiQuotes, TypeFamilies #-}
module Nirum.Targets.Docs ( Docs (..)
, blockToHtml
, makeFilePath
, makeUri
, moduleTitle
) where
import Data.Char
import qualified Data.List
import Data.Maybe
import GHC.Exts (IsList (fromList, toList))
import qualified Data.ByteString as BS
import Data.ByteString.Lazy (toStrict)
import qualified Text.Email.Parser as E
import Data.Map.Strict (Map, mapKeys, mapWithKey, unions)
import qualified Data.Text as T
import qualified Data.Text.Lazy as TL
import Data.Text.Encoding (decodeUtf8, encodeUtf8)
import qualified Data.SemVer
import System.FilePath
import Text.Blaze (ToMarkup (preEscapedToMarkup))
import Text.Blaze.Html.Renderer.Utf8 (renderHtml)
import Text.Cassius
import Text.Hamlet (Html, shamlet)
import Text.InterpolatedString.Perl6 (q)
import Text.Julius
import Nirum.Constructs (Construct (toCode))
import Nirum.Constructs.Declaration (Documented (docsBlock))
import qualified Nirum.Constructs.Declaration as DE
import qualified Nirum.Constructs.DeclarationSet as DES
import qualified Nirum.Constructs.Docs as D
import Nirum.Constructs.Identifier ( Identifier
, toNormalizedString
, toNormalizedText
)
import Nirum.Constructs.Module (Module (Module, docs))
import Nirum.Constructs.ModulePath (ModulePath)
import Nirum.Constructs.Name (Name (facialName))
import qualified Nirum.Constructs.Service as S
import qualified Nirum.Constructs.TypeDeclaration as TD
import qualified Nirum.Constructs.TypeExpression as TE
import Nirum.Docs ( Block (..)
, Inline (..)
, extractTitle
, filterReferences
, transformReferences
, trimTitle
)
import Nirum.Docs.Html (render, renderInlines, renderLinklessInlines)
import Nirum.Package
import Nirum.Package.Metadata hiding (target)
import qualified Nirum.Package.ModuleSet as MS
import Nirum.TypeInstance.BoundModule
import Nirum.Version (versionText)
data Docs = Docs
{ docsTitle :: T.Text
, docsOpenGraph :: [OpenGraph]
, docsStyle :: T.Text
, docsHeader :: T.Text
, docsFooter :: T.Text
} deriving (Eq, Ord, Show)
type Error = T.Text
data CurrentPage
= IndexPage
| ModulePage ModulePath
| DocumentPage FilePath
deriving (Eq, Show)
data OpenGraph = OpenGraph
{ ogTag :: T.Text
, ogContent :: T.Text
} deriving (Eq, Ord, Show)
makeFilePath :: ModulePath -> FilePath
makeFilePath modulePath' = foldl () "" $
map toNormalizedString (toList modulePath') ++ ["index.html"]
-- FIXME: remove trailing index.html on production
makeUri :: ModulePath -> T.Text
makeUri modulePath' =
T.intercalate "/" $
map toNormalizedText (toList modulePath') ++ ["index.html"]
layout :: Package Docs -> Int -> CurrentPage -> T.Text -> Html -> Html
layout pkg dirDepth currentPage title body =
layout' pkg dirDepth currentPage title body Nothing
layout' :: Package Docs
-> Int
-> CurrentPage
-> T.Text
-> Html
-> Maybe Html
-> Html
layout' pkg@Package { metadata = md, modules = ms }
dirDepth currentPage title body footer = [shamlet|
$doctype 5
$if (title == docsTitle (target pkg))
#{title}
$else
#{title} — #{docsTitle (target pkg)}
<meta name="generator" content="Nirum #{versionText}">
$forall Author { name = name' } <- authors md
<meta name="author" content="#{name'}">
$forall OpenGraph { ogTag, ogContent } <- docsOpenGraph $ target pkg
<meta property="#{ogTag}" content="#{ogContent}">
<link rel="stylesheet" href="#{root}style.css">
<link rel="stylesheet" href="#{hljsCss}">
<script src="#{root}nirum.js"></script>
<script src="#{hljsJs}"></script>
<script src="#{root}nirumHighlight.js"></script>
<body>
#{preEscapedToMarkup $ docsHeader $ target pkg}
<nav>
$if currentPage == IndexPage
<a class="index selected" href="#{root}index.html">
<strong>
#{docsTitle $ target pkg}
<small.version>#{Data.SemVer.toText $ version md}
$else
<a class="index" href="#{root}index.html">
<span>
#{docsTitle $ target pkg}
<small.version>#{Data.SemVer.toText $ version md}
$if not (null documentPairs)
<ul.manuals.toc>
$forall (docPath, doc) <- documentPairs
$if currentPage == DocumentPage docPath
<li.selected>
<a href="#{root}#{documentHtmlPath docPath}">
<strong>
#{renderDocumentTitle docPath doc}
$else
<li>
<a href="#{root}#{documentHtmlPath docPath}">
#{renderDocumentTitle docPath doc}
<ul.modules.toc>
$forall (modulePath', mod) <- modulePairs
$if currentPage == ModulePage modulePath'
<li.selected>
<a href="#{root}#{makeUri modulePath'}">
<strong>
<code>#{toCode modulePath'}</code>
$maybe tit <- moduleTitle mod
— #{tit}
$else
<li>
<a href="#{root}#{makeUri modulePath'}">
<code>#{toCode modulePath'}</code>
$maybe tit <- moduleTitle mod
— #{tit}
<article>#{body}
$maybe f <- footer
<footer>#{f}
#{preEscapedToMarkup $ docsFooter $ target pkg}
|]
where
root :: T.Text
root = T.replicate dirDepth "../"
modulePairs :: [(ModulePath, Module)]
modulePairs = MS.toAscList ms
documentPairs :: [(FilePath, D.Docs)]
documentPairs = Data.List.sortOn
documentSortKey
(toList $ fst $ listDocuments pkg)
documentSortKey :: (FilePath, D.Docs) -> (Bool, Int, FilePath)
documentSortKey ("", _) = (False, 0, "")
documentSortKey (fp@(fp1 : _), _) =
(isUpper fp1, length (filter (== pathSeparator) fp), fp)
hljsBase :: T.Text
hljsBase = "https://cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/"
hljsCss :: T.Text
hljsCss = T.concat [hljsBase, "styles/github.min.css"]
hljsJs :: T.Text
hljsJs = T.concat [hljsBase, "highlight.min.js"]
typeExpression :: BoundModule Docs -> TE.TypeExpression -> Html
typeExpression _ expr = [shamlet|#{typeExpr expr}|]
where
typeExpr :: TE.TypeExpression -> Html
typeExpr expr' = [shamlet|
$case expr'
$of TE.TypeIdentifier ident
#{toCode ident}
$of TE.OptionModifier type'
#{typeExpr type'}?
$of TE.SetModifier elementType
{#{typeExpr elementType}}
$of TE.ListModifier elementType
[#{typeExpr elementType}]
$of TE.MapModifier keyType valueType
{#{typeExpr keyType}: #{typeExpr valueType}}
|]
module' :: BoundModule Docs -> Html
module' docsModule =
layout pkg depth (ModulePage docsModulePath) path [shamlet|
$maybe tit <- headingTitle
<h1>
<dfn><code>#{path}</code>
— #{tit}
$nothing
<h1><code>#{path}</code>
$maybe m <- mod'
$maybe d <- docsBlock m
#{blockToHtml (trimTitle d)}
$forall (ident, decl) <- types'
<div class="#{showKind decl}" id="#{toNormalizedText ident}">
#{typeDecl docsModule ident decl}
|]
where
docsModulePath :: ModulePath
docsModulePath = modulePath docsModule
pkg :: Package Docs
pkg = boundPackage docsModule
path :: T.Text
path = toCode docsModulePath
types' :: [(Identifier, TD.TypeDeclaration)]
types' = [ (facialName $ DE.name decl, decl)
| decl <- DES.toList $ boundTypes docsModule
, case decl of
TD.Import {} -> False
_ -> True
]
mod' :: Maybe Module
mod' = resolveModule docsModulePath pkg
headingTitle :: Maybe Html
headingTitle = do
m <- mod'
moduleTitle m
depth :: Int
depth = length $ toList docsModulePath
blockToHtml :: Block -> Html
blockToHtml =
preEscapedToMarkup . render . transformReferences replaceUrl
where
replaceUrl :: T.Text -> T.Text
replaceUrl url
| isAbsoluteUrl url = url
| otherwise =
let (path, frag) = T.break (== '#') url
in T.pack (documentHtmlPath $ T.unpack path) `T.append` frag
isAbsoluteUrl :: T.Text -> Bool
isAbsoluteUrl url
| T.null rest = False
| T.null scheme = True
| otherwise = T.all testChar scheme && isAlpha (T.head scheme)
where
(scheme, rest) = T.break (== ':') url
testChar :: Char -> Bool
testChar c = (isAscii c && isAlphaNum c) || c == '.' || c == '-'
typeDecl :: BoundModule Docs -> Identifier -> TD.TypeDeclaration -> Html
typeDecl mod' ident
tc@TD.TypeDeclaration { TD.type' = TD.Alias cname } = [shamlet|
<h2 id="#{toNormalizedText ident}">
type <dfn><code>#{toNormalizedText ident}</code></dfn> = #
<code.type>#{typeExpression mod' cname}</code>
$maybe d <- docsBlock tc
#{blockToHtml d}
|]
typeDecl mod' ident
tc@TD.TypeDeclaration { TD.type' = TD.UnboxedType innerType } =
[shamlet|
<h2 id="#{toNormalizedText ident}">
unboxed
<dfn><code>#{toNormalizedText ident}</code>
(<code>#{typeExpression mod' innerType}</code>)
$maybe d <- docsBlock tc
#{blockToHtml d}
|]
typeDecl _ ident
tc@TD.TypeDeclaration { TD.type' = TD.EnumType members } = [shamlet|
<h2 id="#{toNormalizedText ident}">
enum <dfn><code>#{toNormalizedText ident}</code></dfn>
$maybe d <- docsBlock tc
#{blockToHtml d}
<dl class="members">
$forall decl <- DES.toList members
<dt class="member-name">
<code>#{nameText $ DE.name decl}
<dd class="member-doc">
$maybe d <- docsBlock decl
#{blockToHtml d}
|]
typeDecl mod' ident
tc@TD.TypeDeclaration { TD.type' = TD.RecordType fields } = [shamlet|
<h2 id="#{toNormalizedText ident}">
record <dfn><code>#{toNormalizedText ident}</code></dfn>
$maybe d <- docsBlock tc
#{blockToHtml d}
<dl.fields>
$forall fieldDecl@(TD.Field _ fieldType _) <- DES.toList fields
<dt>
<code.type>#{typeExpression mod' fieldType}
<var><code>#{nameText $ DE.name fieldDecl}</code>
<dd>
$maybe d <- docsBlock fieldDecl
#{blockToHtml d}
|]
typeDecl mod' ident
tc@TD.TypeDeclaration
{ TD.type' = unionType@TD.UnionType
{ TD.defaultTag = defaultTag
}
} =
[shamlet|
<h2 id="#{toNormalizedText ident}">
union <dfn><code>#{toNormalizedText ident}</code></dfn>
$maybe d <- docsBlock tc
#{blockToHtml d}
$forall (default_, tagDecl@(TD.Tag _ fields _)) <- tagList
<h3 .tag :default_:.default-tag>
$if default_
default tag #
$else
tag #
<dfn><code>#{nameText $ DE.name tagDecl}</code>
$maybe d <- docsBlock tagDecl
#{blockToHtml d}
<dl.fields>
$forall fieldDecl@(TD.Field _ fieldType _) <- DES.toList fields
<dt>
<code.type>#{typeExpression mod' fieldType}
<var><code>#{nameText $ DE.name fieldDecl}</code>
<dd>
$maybe d <- docsBlock fieldDecl
#{blockToHtml d}
|]
where
tagList :: [(Bool, TD.Tag)]
tagList =
[ (defaultTag == Just tag, tag)
| tag <- DES.toList (TD.tags unionType)
]
typeDecl _ ident
TD.TypeDeclaration { TD.type' = TD.PrimitiveType {} } = [shamlet|
<h2 id="#{toNormalizedText ident}">
primitive <code>#{toNormalizedText ident}</code>
|]
typeDecl mod' ident
tc@TD.ServiceDeclaration { TD.service = S.Service methods } =
[shamlet|
<h2 id="#{toNormalizedText ident}">
service <dfn><code>#{toNormalizedText ident}</code></dfn>
$maybe d <- docsBlock tc
#{blockToHtml d}
$forall md@(S.Method _ ps ret err _) <- DES.toList methods
<h3.method>
$maybe retType <- ret
<span.return>
<code.type>#{typeExpression mod' retType}
<dfn>
<code>#{nameText $ DE.name md}
<span.parentheses>()
$maybe errType <- err
<span.error>
throws
<code.error.type>#{typeExpression mod' errType}
$maybe d <- docsBlock md
#{blockToHtml d}
<dl.parameters>
$forall paramDecl@(S.Parameter _ paramType _) <- DES.toList ps
$maybe d <- docsBlock paramDecl
<dt>
<code.type>#{typeExpression mod' paramType}
<code><var>#{nameText $ DE.name paramDecl}</var>
<dd>#{blockToHtml d}
|]
typeDecl _ _ TD.Import {} =
error ("It shouldn't happen; please report it to Nirum's bug tracker:\n" ++
"https://github.com/nirum-lang/nirum/issues")
nameText :: Name -> T.Text
nameText = toNormalizedText . facialName
showKind :: TD.TypeDeclaration -> T.Text
showKind TD.ServiceDeclaration {} = "service"
showKind TD.TypeDeclaration { TD.type' = type'' } = case type'' of
TD.Alias {} -> "alias"
TD.UnboxedType {} -> "unboxed"
TD.EnumType {} -> "enum"
TD.RecordType {} -> "record"
TD.UnionType {} -> "union"
TD.PrimitiveType {} -> "primitive"
showKind TD.Import {} = "import"
readmePage :: Package Docs -> D.Docs -> Html
readmePage pkg docs' =
layout pkg 0 IndexPage (docsTitle $ target pkg) content
where
content :: Html
content = blockToHtml $ D.toBlock docs'
documentPage :: Package Docs -> FilePath -> D.Docs -> Html
documentPage pkg filePath docs' =
layout pkg depth (DocumentPage filePath) title' content
where
title' :: T.Text
title' = documentTitleText filePath docs'
content :: Html
content = blockToHtml $ D.toBlock docs'
depth :: Int
depth = length (splitPath (documentHtmlPath filePath)) - 1
documentHtmlPath :: FilePath -> FilePath
documentHtmlPath = (-<.> "html")
documentTitle :: FilePath -> D.Docs -> [Inline]
documentTitle filePath document =
case extractTitle $ D.toBlock document of
Just (_, inlines) -> inlines
Nothing -> [Text $ T.pack filePath]
renderDocumentTitle :: FilePath -> D.Docs -> Html
renderDocumentTitle filePath =
preEscapedToMarkup . renderLinklessInlines . documentTitle filePath
documentTitleText :: FilePath -> D.Docs -> T.Text
documentTitleText filePath =
renderInlines' . documentTitle filePath
where
renderInline :: Inline -> T.Text
renderInline (Text t) = t
renderInline SoftLineBreak = "\n"
renderInline HardLineBreak = "\n"
renderInline (HtmlInline _) = ""
renderInline (Code code') = code'
renderInline (Emphasis inlines) = renderInlines inlines
renderInline (Strong inlines) = renderInlines inlines
renderInline (Link _ _ inlines) = renderInlines inlines
renderInline (Image _ title)
| T.null title = ""
| otherwise = title
renderInlines' :: [Inline] -> T.Text
renderInlines' = T.concat . fmap renderInline
contents :: Package Docs -> Html
contents pkg@Package { metadata = md
, modules = ms
} =
layout' pkg 0 IndexPage title body $ case authors md of
[] -> Nothing
_ : _ -> Just footer
where
body :: Html
body = [shamlet|
<h1>Modules
$forall (modulePath', mod) <- MS.toAscList ms
<h2>
<a href="#{makeUri modulePath'}">
<code>#{toCode modulePath'}</code>
$maybe tit <- moduleTitle mod
— #{tit}
|]
title :: T.Text
title = docsTitle $ target pkg
footer :: Html
footer = [shamlet|
<dl>
<dt.author>
$if 1 < length (authors md)
Authors
$else
Author
$forall Author { name = n, uri = u, email = e } <- authors md
$maybe uri' <- u
<dd.author><a href="#{show uri'}">#{n}</a>
$nothing
$maybe email' <- e
<dd.author><a href="mailto:#{emailText email'}">#{n}</a>
$nothing
<dd.author>#{n}
|]
emailText :: E.EmailAddress -> T.Text
emailText = decodeUtf8 . E.toByteString
moduleTitle :: Module -> Maybe Html
moduleTitle Module { docs = docs' } = do
d <- docs'
t <- D.title d
nodes <- case t of
Heading _ inlines _ ->
Just $ filterReferences inlines
_ -> Nothing
return $ preEscapedToMarkup $ renderInlines nodes
stylesheet :: TL.Text
stylesheet = renderCss ([cassius|
@import url(#{fontUrl})
body
padding: 0
margin: 0
font-family: Source Sans Pro
color: #{gray8}
article
line-height: 1.3
code
font-family: Source Code Pro
font-weight: 300
background-color: #{gray1}
strong code
font-weight: 400
pre
padding: 16px 10px
background-color: #{gray1}
code, code.hljs
background: none
div
border-top: 1px solid #{gray3}
h1, h2, h3, h4, h5, h6
code
background-color: #{gray3}
h1, h2, h3, h4, h5, h6, dt
font-weight: bold
code
font-weight: 400
h2 a.pilcrow
visibility: hidden
margin-left: 10px
h2:hover a.pilcrow
visibility: visible
a
text-decoration: none
a:link
color: #{indigo8}
a:visited
color: #{graph8}
a:hover
text-decoration: underline
dd
p
margin-top: 0
nav
position: fixed
left: 0
top: 0
bottom: 0
width: #{navWidth}
overflow-y: auto
border-right: 1px solid #{gray2}
background-color: #{gray0}
code
background: none
a.index, ul.toc li a
display: block
padding: 0 1em
margin: 1em 0
overflow: hidden
white-space: nowrap
text-overflow: ellipsis
color: #{gray8}
.selected > a, a.selected
color: #{indigo8} !important
a.index
text-decoration: none
.version
margin-left: 0.2em
color: #{gray5}
.version:before
content: '('
.version:after
content: ')'
a.index.selected .version
color: #{indigo3}
a.index:hover
span, strong
text-decoration: underline
ul.toc
margin: 0
padding: 0
border-top: 1px solid #{gray2}
li
display: block
article, footer
margin-left: #{navWidth}
padding: 1em
> h1, > h2, > h3, > h4, > h5, > h6, > dl
&:first-child
margin-top: 0
footer
border-top: 1px solid #{gray2}
|] undefined)
where
fontUrl :: T.Text
fontUrl = T.concat
[ "https://fonts.googleapis.com/css"
, "?family=Source+Code+Pro:300,400|Source+Sans+Pro"
]
-- from Open Color https://yeun.github.io/open-color/
gray0 :: Color
gray0 = Color 0xf8 0xf9 0xfa
gray1 :: Color
gray1 = Color 0xf1 0xf3 0xf5
gray2 :: Color
gray2 = Color 0xe9 0xec 0xef
gray3 :: Color
gray3 = Color 0xde 0xe2 0xe6
gray5 :: Color
gray5 = Color 0xad 0xb5 0xbd
gray8 :: Color
gray8 = Color 0x34 0x3a 0x40
graph8 :: Color
graph8 = Color 0x9c 0x36 0xb5
indigo3 :: Color
indigo3 = Color 0x91 0xa7 0xff
indigo8 :: Color
indigo8 = Color 0x3b 0x5b 0xdb
navWidth :: PixelSize
navWidth = PixelSize 300
javascript :: T.Text
javascript = [q|
window.addEventListener('load', function () {
document.querySelectorAll('h2[id]').forEach(function(node) {
var anchor = document.createElement("a");
anchor.className = "pilcrow";
anchor.text = "\xb6";
anchor.href = "#" + node.id;
node.appendChild(anchor);
});
});
|]
nirumHighlightJavascript :: TL.Text
nirumHighlightJavascript = renderJavascript ([julius|
hljs.registerLanguage('nirum', function(hljs) {
// Unfortunately CDN for highlight.js does not deliver
// non-bundled unminified source, so we minify it by hand.
// See also:
// https://github.com/highlightjs/highlight.js/blob/master/tools/utility.js
var begin = 'b';
var beginKeywords = 'bK';
var className = 'cN';
var contains = 'c';
var end = 'e';
var excludeEnd = 'eE';
var keywords = 'k';
var relevance = 'r';
var C_LINE_COMMENT_MODE = hljs.CLCM;
var HASH_COMMENT_MODE = hljs.HCM;
var APOS_STRING_MODE = hljs.ASM;
var QUOTE_STRING_MODE = hljs.QSM;
var NUMBER_MODE = hljs.NM;
var NIRUM_IDENTIFIER_RE = '(`)?[a-zA-Z][a-zA-Z0-9\\-_]*\\1';
var NIRUM_IDENTIFIER_MODE = {
[className]: 'title',
[begin]: NIRUM_IDENTIFIER_RE,
[relevance]: 0,
};
return {
[keywords]: {
keyword: 'record enum unboxed type union service' +
' import throws as default',
built_in: 'bigint decimal int32 int64 float32 float64' +
' text binary datetime date bool uuid uri',
},
[contains]: [
// comments
C_LINE_COMMENT_MODE,
HASH_COMMENT_MODE,
// string literals
APOS_STRING_MODE,
QUOTE_STRING_MODE,
// number literals
NUMBER_MODE,
// annotations
{
[className]: 'meta',
[begin]: '@\\\s*' + NIRUM_IDENTIFIER_RE,
},
// typedefs
{
[className]: 'class',
[beginKeywords]: 'enum record union service',
[end]: '[\\(=]',
[excludeEnd]: true,
[contains]: [
C_LINE_COMMENT_MODE,
HASH_COMMENT_MODE,
NIRUM_IDENTIFIER_MODE,
]
},
],
}
});
hljs.initHighlightingOnLoad();
|] undefined :: Javascript)
compilePackage' :: Package Docs -> Map FilePath (Either Error BS.ByteString)
compilePackage' pkg = unions
[ fromList
[ ("style.css", Right $ encodeUtf8 css)
, ("nirum.js", Right $ encodeUtf8 javascript)
, ( "nirumHighlight.js"
, Right $ encodeUtf8 $ TL.toStrict nirumHighlightJavascript
)
, ( "index.html"
, Right $ toStrict $ renderHtml $ case readme of
Nothing -> contents pkg
Just readme' -> readmePage pkg readme'
)
]
, fromList
[ ( makeFilePath $ modulePath m
, Right $ toStrict $ renderHtml $ module' m
)
| m <- modules'
]
, mapKeys documentHtmlPath $
fmap
(Right . toStrict . renderHtml)
(mapWithKey (documentPage pkg) documents')
]
where
paths' :: [ModulePath]
paths' = MS.keys $ modules pkg
modules' :: [BoundModule Docs]
modules' = mapMaybe (`resolveBoundModule` pkg) paths'
css = T.concat [TL.toStrict stylesheet, "\n\n", docsStyle $ target pkg]
(documents', readme) = listDocuments pkg
listDocuments :: Package Docs -> (Map FilePath D.Docs, Maybe D.Docs)
listDocuments Package { documents = documents' } =
case Data.List.break (isReadme . fst) pairs of
(a, (_, readme) : b) -> (fromList (a ++ b), Just readme)
(a, []) -> (fromList a, Nothing)
where
isReadme :: FilePath -> Bool
isReadme fp = "readme.md" == map toLower (takeFileName fp)
pairs :: [(FilePath, D.Docs)]
pairs = toList documents'
instance Target Docs where
type CompileResult Docs = BS.ByteString
type CompileError Docs = Error
targetName _ = "docs"
parseTarget table = do
title <- stringField "title" table
opengraphs <- optional $ opengraphsField "opengraphs" table
style <- optional $ stringField "style" table
header <- optional $ stringField "header" table
footer <- optional $ stringField "footer" table
return Docs
{ docsTitle = title
, docsOpenGraph = fromMaybe [] opengraphs
, docsStyle = fromMaybe "" style
, docsHeader = fromMaybe "" header
, docsFooter = fromMaybe "" footer
}
compilePackage = compilePackage'
showCompileError _ = id
toByteString _ = id
opengraphsField :: MetadataField -> Table -> Either MetadataError [OpenGraph]
opengraphsField field' table = do
array <- tableArrayField field' table
opengraphs' <- mapM parseOpenGraph array
return $ toList opengraphs'
where
parseOpenGraph :: Table -> Either MetadataError OpenGraph
parseOpenGraph t = do
tag' <- stringField "tag" t
content' <- stringField "content" t
return OpenGraph
{ ogTag = tag'
, ogContent = content'
}