frontmatter: Parses frontmatter as used in Jekyll markdown files.

[ data, library, mit ] [ Propose Tags ]
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Dependencies attoparsec (>=, base (==4.*), bytestring, yaml [details]
License MIT
Copyright Copyright (c) 2015 Pedro Tacla Yamada
Author Pedro Tacla Yamada
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Source repo head: git clone git://
Uploaded by yamadapc at Sun Dec 20 03:46:12 UTC 2015
Distributions LTSHaskell:, NixOS:, Stackage:, openSUSE:
Downloads 728 total (13 in the last 30 days)
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Status Docs available [build log]
Last success reported on 2015-12-20 [all 1 reports]
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Parses frontmatter as used in Jekyll markdown files.

Provides a parser that'll parse the frontmatter only and one that'll execute a YAML parser on it, so that it's a YAML frontmatter parser.

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Readme for frontmatter-

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Attoparsec parsers for YAML frontmatter as used in Jekyll. Because of how Data.Yaml is implemented using Data.Aeson, the Data.Yaml.Frontmatter.frontmatterYaml instance of Parser works with YAML and JSON.


This actually won't work right now

$ stack install frontmatter


import Data.Frontmatter
import Data.Yaml (Value)

main = ByteString.readFile "" >>= parseYamlFrontmatter >>= \case
    Done ri fm -> do
        print (fm :: Value) -- aeson object in the frontmatter (the explicit
                            -- type required because the parser will return
                            -- anything with a FromJSON

        putStrLn ri         -- rest of the document
    _ -> error "Parse failure"

See the haddocks for more information. Essentially exports an Attoparsec parser and some helpers. Usage examples also available at the test directory.


I'm working on the Haskell workshop tool workhs. In my mind, using markdown file names as metadata is a very sensible decision. However, I'd like for tutorial writers to be able to override metadata. Then, Jekyll's YAML frontmatter format is a great choice:

  • It's familiar
  • It's very, very easy to implement


This software is published under the MIT license. For more information refer to the LICENSE file.