========================= Pesto specification draft ========================= 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 `_ intended 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. Being a literate program this document is specification and reference implementation at the same time. 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/ :Discussion: https://github.com/PromyLOPh/pesto :Contributors: - `Lars-Dominik Braun `_ .. _CC0: https://creativecommons.org/publicdomain/zero/1.0/ .. _motivation: Motivation ---------- The landscape of recipe interchange formats is quite fragmented. First of all there’s HTML microdata. `Google rich snippets`_, which are 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 do so, because it is considered a search-engine optimization (SEO). Additionally parsing HTML pulled from the web is a nightmare and thus not a real option for sharing recipes. h-recipe_ provides a second vocabulary, but has not been adopted widely. .. _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 Mealmaster_, an ancient file format with – due to its age – many problems, seems to have the most traction right now. A large amount of recipe files is `available in this format `_. Rezkonv_ aims to improve the Mealmaster format. However the specification is available on request only. Another text-based format, MXP_ (plus MX2, MZ2), is used by Mastercook. A newer format, YumML_, is based on YAML. The specification has been removed from the web and is available through the Web Archive only. .. _xml-formats: There’s a number of XML-based formats: RecipeML_, formerly known as DESSERT was 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. REML_ was released in 2005 (version 0.5). It is rather complicated and has no license. `RecipeBook XML`_, released in 2005 as well and shared unter the terms of `CC by-sa`_ is not available on the web any more. CookML_, created in 2006 (version 1.0.4) for the german-language shareware program Kalorio has a custom and restrictive licence that requires attribution and forbids derivate works. KRecipes_ uses its own export format. However there is no documentation whatsoever. Gourmet_’s export format suffers from the same problem. The only document available is the `DTD `_. .. _CC by-sa: https://creativecommons.org/licenses/by-sa/2.5/ All of the formats above share a common design aspect: They split recipes into two parts, ingredients and instructions. This is quite odd given the nature of cooking recipes. RxOL_, created in 1985, represents recipes as a graph with postfix notation and minimal “chitchat”. Although Pesto is not a direct descendant of RxOL it’s syntax and semantics are quite similar. .. _REML: http://reml.sourceforge.net/ .. _RecipeML: http://www.formatdata.com/recipeml/index.html .. _CookML: http://www.kalorio.de/index.php?Mod=Ac&Cap=CE&SCa=../cml/CookML_EN .. _Mealmaster: http://www.wedesoft.de/anymeal-api/mealmaster.html .. _MXP: http://www.oocities.org/heartland/woods/2073/Appendix.htm .. _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://www.dodomagnifico.com/641/Recipes/CompCook.html .. _Gourmet: http://thinkle.github.io/gourmet/ .. _KRecipes: http://krecipes.sourceforge.net/ .. 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 ----- 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 not suitable and the interchange formats listed `above `_ have largely failed to gain traction. XML, even though simple itself, 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”. A good example for this is Markdown_. .. _Markdown: https://daringfireball.net/projects/markdown/syntax We also have to acknowledge that machines play an important role in our daily life. They can help us, the users, accomplish our goals if they are able to understand the recipes as well. 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 itself. 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 ----------------------- So let’s start by introducing Pesto in a XXXnon-formal, XXX way: By example. We are now going to cook XXX. The following recipe contains all the information you need to do that. .. class:: todo do it. See https://github.com/PromyLOPh/rezepte for example recipes. .. include:: Pesto/Parse.lhs .. include:: Pesto/Graph.lhs .. include:: Pesto/Lint.lhs .. include:: Pesto/Dot.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:: ../Main.lhs .. include:: ../Test.lhs .. include:: ../Doc.lhs Final words ----------- .. class:: todo Do we even need this?