============================ Pesto language specification ============================ Pesto is a text-based, human-editable, and machine-transformable cooking recipe interchange format. .. class:: nodoc > module Codec.Pesto where About this document ------------------- This section contains various information about this document. The `second section`__ motivates why inventing another file format is necessary, followed by the goals__ of Pesto. After a short Pesto primer__ for the casual user, the language’s syntax__ and semantics__ are presented. The `linting section`__ limits the language to useful cooking recipes. Examples for user presentation of recipes and serialization follow. __ #motivation __ #goals __ #introduction-by-example __ #language-syntax __ #language-semantics __ #linting Being a literate program, this document is specification and reference implementation simultaneously. The code is written in Haskell_ and uses the parsec_ parser combinator library, as well as HUnit_ for unit tests. Even without knowing Haskell’s syntax, you should be able to understand this specification. There’s a description above every code snippet explaining what is going on. .. _Haskell: http://learnyouahaskell.com/ .. _HUnit: http://hackage.haskell.org/package/HUnit .. _parsec: http://hackage.haskell.org/package/parsec The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in `RFC 2119`_. .. _RFC 2119: http://tools.ietf.org/html/rfc2119 :Version: 1-draft :License: CC0_ :Website: https://6xq.net/pesto/ :Source code: https://codeberg.org/ldb/pesto .. _CC0: https://creativecommons.org/publicdomain/zero/1.0/ .. _motivation: Motivation ---------- The landscape of recipe interchange formats is quite fragmented. First, there’s HTML microdata: `Google rich snippets`_, equivalent to the schema.org_ microdata vocabulary, are widely used by commercial recipe sites. Although the main objective of microdata is to make content machine-readable most sites will probably use it because it is considered a search-engine optimization (SEO) and not a method for sharing recipes. h-recipe_ provides a second vocabulary that has not been adopted widely yet. .. _Google rich snippets: https://developers.google.com/structured-data/rich-snippets/recipes .. _schema.org: http://schema.org/Recipe .. _h-recipe: http://microformats.org/wiki/h-recipe .. _formats-by-software: Most cooking-related software comes with custom recipe file formats. Some of them can be imported by other programs. Meal-Master_ is one of these widely supported formats. A vast trove of recipe files is `available in this format `_. There does not seem to be any official documentation for the format, but inofficial `ABNF grammar`_ and `format description `_ exist. A Meal-Master recipe template might look like this: .. _MasterCook: http://mastercook.com/ .. _MXP: http://www.oocities.org/heartland/woods/2073/Appendix.htm .. _ABNF grammar: http://web.archive.org/web/20161002135718/http://www.wedesoft.de/anymeal-api/mealmaster.html .. code:: mealmaster ---------- Recipe via Meal-Master (tm) Title: Categories: <Categories> Yield: <N servings> <N> <unit> <ingredient> … -------------------------------<Section name>----------------------------- <More ingredients> <Instructions> ----- Rezkonv_ aims to improve the Mealmaster format by lifting some of its character limits, adding new syntax, and translating it to german. However, the specification is available on request only. A second format some programs can import is MasterCook_’s MXP_ file format and its XML-based successor, MX2. Beyond that there exist numerous application-specific, proprietary formats: `Living Cookbook`_ Uses a XML-based format called fdx version 1.1. There’s no specification to be found, but a few `examples <http://livingcookbook.com/Resource/DownloadableRecipes>`_ are available, and those are dated 2006. `My CookBook`_ Uses the file extension .mcb. A specification `is available <http://mycookbook-android.com/site/my-cookbook-xml-schema/>`_. KRecipes_ Uses its own export format. However, there is no documentation whatsoever. Gourmet_ The program’s export format suffers from the same problem. The only document available is the `DTD <https://github.com/thinkle/gourmet/blob/7715c6ef87ee8c106f0a021972cd70d61d83cadb/data/recipe.dtd>`_. CookML_ Last updated in 2006 (version 1.0.4) for the german-language shareware program Kalorio has a custom and restrictive license that requires attribution and forbids derivate works. Paprika_ Cross-platform application which supports its own “emailed recipe format” and a simple YAML-based format. .. _Paprika: https://paprikaapp.com/help/android/#importrecipes .. _xml-formats: Between 2002 and 2005, a bunch of XML-based exchange formats were created. They are not tied to specific software, so none of them seems to be actively used nowadays: RecipeML_ Formerly known as DESSERT and released in 2002 (version 0.5). The license requires attribution and – at the same time – forbids using the name RecipeML for promotion without written permission. eatdrinkfeelgood_ Version 1.1 was released in 2002 as well, but the site is not online anymore. The DTD is licensed under the `CC by-sa`_ license. REML_ Released in 2005 (version 0.5), aims to improve support for commercial uses (restaurant menus and cookbooks). The XSD’s license allows free use and redistribution, but the reference implementation has no licensing information. `RecipeBook XML`_ Released 2005 as well and shared under the terms of `CC by-sa`_ is not available on the web anymore. .. _CC by-sa: https://creativecommons.org/licenses/by-sa/2.5/ .. _obscure-formats: Finally, a few non-XML or obscure exchange formats have been created in the past: YumML_ is an approach similar to those listed above but based on YAML instead of XML. The specification has been removed from the web and is available through the Web Archive only. `Cordon Bleu`_ (1999) encodes recipes as programs for a cooking machine and defines a Pascal-like language. Being so close to real programming languages, Cordon Bleu is barely usable by anyone except programmers. Additionally, the language is poorly-designed since its syntax is inconsistent, and the user is limited to a set of predefined functions. Finally, there is RxOL_, created in 1985. It constructs a graph from recipes written down with a few operators and postfix notation, and does not separate ingredients and cooking instructions like every other syntax introduced before. Although Pesto is not a direct descendant of RxOL both share many ideas. microformats.org_ has a similar list of recipe interchange formats. .. _REML: http://reml.sourceforge.net/ .. _eatdrinkfeelgood: https://web.archive.org/web/20070109085643/http://eatdrinkfeelgood.org/1.1/ .. _RecipeML: http://www.formatdata.com/recipeml/index.html .. _CookML: http://www.kalorio.de/index.php?Mod=Ac&Cap=CE&SCa=../cml/CookML_EN .. _Meal-Master: http://web.archive.org/web/20151029032924/http://episoft.home.comcast.net:80/~episoft/ .. _RecipeBook XML: http://web.archive.org/web/20141101132332/http://www.happy-monkey.net/recipebook/ .. _YumML: http://web.archive.org/web/20140703234140/http://vikingco.de/yumml.html .. _Rezkonv: http://www.rezkonv.de/software/rksuite/rkformat.html .. _RxOL: http://web.archive.org/web/20150814041516/www.dodomagnifico.com/641/Recipes/CompCook.html .. _Gourmet: http://thinkle.github.io/gourmet/ .. _KRecipes: http://krecipes.sourceforge.net/ .. _Cordon Bleu: http://web.archive.org/web/20090115210732/http://www.inf.unideb.hu/~bognar/ps_ek/cb_lang.ps .. _microformats.org: http://microformats.org/wiki/recipe-formats .. _Living Cookbook: http://livingcookbook.com/ .. _My CookBook: http://mycookbook-android.com/ .. There is a copy at http://diyhpl.us/~bryan/papers2/CompCook.html as well .. More interesting stuff: .. - http://blog.moertel.com/posts/2010-01-08-a-formal-language-for-recipes-brain-dump.html .. - http://www.dangermouse.net/esoteric/chef.html .. _goals: Goals ----- First of all, recipes are written *by* humans *for* humans. Thus a human-readable recipe interchange format is not enough. The recipes need to be human-editable without guidance like a GUI or assistant. That’s why, for instance, XML is unsuitable, and the interchange formats listed `above <xml-formats_>`_ have largely failed to gain traction. Even though simple, XML is still too complicated for the ordinary user. Instead, a format needs to be as simple as possible, with as little markup as possible. A human editor must be able to remember the entire syntax. This works best if the file contents “make sense.” An excellent example of this is Markdown_. .. _Markdown: https://daringfireball.net/projects/markdown/syntax We also must acknowledge that machines play an important role in our daily lives. They can help us, the users, accomplish our goals if they can also understand the recipes. Thus they, too, need to be able to read and write recipes. Again, designing a machine-readable format is not enough. Recipes must be machine-transformable. A computer program should be able to create a new recipe from two existing ones, look up the ingredients and tell us how many joules one piece of that cake will have. And so on. That being said, Pesto does not aim to carry additional information about ingredients or recipes themselves. Nutrition data for each ingredient should be maintained in a separate database. Due to its minimal syntax, Pesto is also not suitable for extensive guides on cooking or the usual chitchat found in cooking books. .. _introduction-by-example: Introduction by example ----------------------- .. code:: So let’s start by introducing Pesto by example. This text does not belong to the recipe and is ignored by any software. The following line starts the recipe: %pesto &pot +1 l water +salt [boil] +100 g penne &10 min [cook] >1 serving pasta (language: en) And that’s how you make pasta: Boil one liter of water in a pot with a little bit of salt. Then add 100 g penne, cook them for ten minutes, and you get one serving pasta. That’s all. There’s more syntax available to express alternatives (either penne or tagliatelle), ranges (1–2 l water or approximately 1 liter water), and metadata. But now you can have a first peek at `my recipe collection`_. .. _my recipe collection: https://codeberg.org/ldb/rezepte .. include:: Pesto/Parse.lhs .. include:: Pesto/Graph.lhs .. include:: Pesto/Lint.lhs .. include:: Pesto/Serialize.lhs Using this project ------------------ This project uses cabal. It provides the ``Codec.Pesto`` library that implements the Pesto language as described in the previous sections. It also comes with three binaries. .. include:: ../../exe/Main.lhs .. include:: ../../exe/Test.lhs .. include:: ../../exe/Doc.lhs