{"id":16965070,"url":"https://github.com/propensive/adversaria","last_synced_at":"2025-03-17T08:37:47.092Z","repository":{"id":56206769,"uuid":"167544930","full_name":"propensive/adversaria","owner":"propensive","description":"Typeclass interfaces to access user-defined Scala annotations","archived":false,"fork":false,"pushed_at":"2025-02-12T18:54:52.000Z","size":2245,"stargazers_count":24,"open_issues_count":4,"forks_count":0,"subscribers_count":3,"default_branch":"main","last_synced_at":"2025-03-10T19:53:46.286Z","etag":null,"topics":["annotations","java-annotations","scala","tags","typeclass"],"latest_commit_sha":null,"homepage":"https://propensive.com/adversaria/","language":"Scala","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/propensive.png","metadata":{"files":{"readme":".github/readme.md","changelog":null,"contributing":".github/contributing.md","funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2019-01-25T12:35:25.000Z","updated_at":"2025-02-12T18:54:56.000Z","dependencies_parsed_at":"2024-02-27T10:02:06.045Z","dependency_job_id":"f3bb7aa9-e3d4-4ed4-b9f8-e2511e7dc172","html_url":"https://github.com/propensive/adversaria","commit_stats":null,"previous_names":[],"tags_count":3,"template":false,"template_full_name":null,"repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/propensive%2Fadversaria","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/propensive%2Fadversaria/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/propensive%2Fadversaria/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/propensive%2Fadversaria/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/propensive","download_url":"https://codeload.github.com/propensive/adversaria/tar.gz/refs/heads/main","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":243852499,"owners_count":20358271,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["annotations","java-annotations","scala","tags","typeclass"],"created_at":"2024-10-13T23:44:56.467Z","updated_at":"2025-03-17T08:37:47.083Z","avatar_url":"https://github.com/propensive.png","language":"Scala","readme":"[\u003cimg alt=\"GitHub Workflow\" src=\"https://img.shields.io/github/actions/workflow/status/propensive/adversaria/main.yml?style=for-the-badge\" height=\"24\"\u003e](https://github.com/propensive/adversaria/actions)\n[\u003cimg src=\"https://img.shields.io/discord/633198088311537684?color=8899f7\u0026label=DISCORD\u0026style=for-the-badge\" height=\"24\"\u003e](https://discord.com/invite/MBUrkTgMnA)\n\u003cimg src=\"/doc/images/github.png\" valign=\"middle\"\u003e\n\n# Adversaria\n\n__Providing typeclass interfaces to user-defined Scala annotations__\n\n__Adversaria__ is a tiny library which provides a few tools to make it easier to work with static\n_annotations_ in Scala, by making them available through _typeclass interfaces_.\n\n## Features\n\n- access all annotations on a type through a typeclass\n- resolve a typeclass instance only if a type has an annotated field\n- makes annotations more useful and accessible in Scala\n- no macro code is required to use annotations\n\n\n## Availability\n\n\n\n\n\n\n\n## Getting Started\n\nAnnotations in Scala are rarely the best solution for any task, but can\nnevertheless be convenient as a \"feature of last resort\" when no other solution\nprovides the right ergonomics. This small domain is where Adversaria helps.\n\nCurrently three use cases are supported:\n- getting all the annotations applied to a particular type\n- finding the particular parameter of a case class to which a certain\n  annotation has been applied\n- getting every annotation applied to a particular case class field\n\nThis list of supported use cases is likely to grow.\n\n### Annotations\n\nIf we define the following annotations in the standard way (each starting with\na lower-case letter, as is the convention)\n```scala\nimport scala.annotation.StaticAnnotation\n\nfinal case class id() extends StaticAnnotation\nfinal case class count(n: Int) extends StaticAnnotation\n```\nwe could apply them to some case classes, such as:\n```scala\n@count(10)\ncase class Company(name: Text)\ncase class Person(name: Text, @id email: Text)\n```\n\nWe would like to write code that can access annotations such as `@count` and\n`@id` through a simple typeclass interface.\n\n### Contextual evidence\n\nElsewhere, we may have a polymorphic method, say `inspect`, which inspects an\ninstance of a type:\n```scala\ndef inspect[T](value: T): Unit\n```\n\nIf we would like to get the annotations on `T` that are subtypes of `count`, we\ncan get these with the typeclass, `Annotations`:\n```scala\ndef inspect[T](value: T)(using anns: Annotations[count, T]): Unit =\n  anns.collect:\n    case `count`(n: Int) =\u003e println(t\"count = $n\")\n```\n\nIf `inspect` is called with a type, `T`, that does not have any `@count`\nannotations, then no contextual `Annotations[count, T]` instance will be\nconstructed, and the code will not compile. So `inspect[Company](company)`\nwould compile, while `inspect[Person](person)` would not.\n\n### Direct inspection\n\nThree methods also provide access to annotations on fields:\n- `Annotations.field[T](fn)` will return a list of annotations on the case\n  class field indicated by the lambda, `fn`. This lambda must be a simple field\naccessor, such as `_.email`, otherwise the method will not compile.\n- `Annotations.fields[T, A]` will return a list of `CaseField` instances\n  providing access to the name, annotation and value (if given an instance of\n`T` to dereference) for each annotation on any field with an annotation of type\n`A` in `T`'s definition.\n- `Annotations.firstField[T, A]` will return the first such field, if it exists.\n\n\n\n\n\n\n\n## Status\n\nAdversaria is classified as __fledgling__. For reference, Soundness projects are\ncategorized into one of the following five stability levels:\n\n- _embryonic_: for experimental or demonstrative purposes only, without any guarantees of longevity\n- _fledgling_: of proven utility, seeking contributions, but liable to significant redesigns\n- _maturescent_: major design decisions broady settled, seeking probatory adoption and refinement\n- _dependable_: production-ready, subject to controlled ongoing maintenance and enhancement; tagged as version `1.0.0` or later\n- _adamantine_: proven, reliable and production-ready, with no further breaking changes ever anticipated\n\nProjects at any stability level, even _embryonic_ projects, can still be used,\nas long as caution is taken to avoid a mismatch between the project's stability\nlevel and the required stability and maintainability of your own project.\n\nAdversaria is designed to be _small_. Its entire source code currently consists\nof 148 lines of code.\n\n## Building\n\nAdversaria will ultimately be built by Fury, when it is published. In the\nmeantime, two possibilities are offered, however they are acknowledged to be\nfragile, inadequately tested, and unsuitable for anything more than\nexperimentation. They are provided only for the necessity of providing _some_\nanswer to the question, \"how can I try Adversaria?\".\n\n1. *Copy the sources into your own project*\n   \n   Read the `fury` file in the repository root to understand Adversaria's build\n   structure, dependencies and source location; the file format should be short\n   and quite intuitive. Copy the sources into a source directory in your own\n   project, then repeat (recursively) for each of the dependencies.\n\n   The sources are compiled against the latest nightly release of Scala 3.\n   There should be no problem to compile the project together with all of its\n   dependencies in a single compilation.\n\n2. *Build with [Wrath](https://github.com/propensive/wrath/)*\n\n   Wrath is a bootstrapping script for building Adversaria and other projects in\n   the absence of a fully-featured build tool. It is designed to read the `fury`\n   file in the project directory, and produce a collection of JAR files which can\n   be added to a classpath, by compiling the project and all of its dependencies,\n   including the Scala compiler itself.\n   \n   Download the latest version of\n   [`wrath`](https://github.com/propensive/wrath/releases/latest), make it\n   executable, and add it to your path, for example by copying it to\n   `/usr/local/bin/`.\n\n   Clone this repository inside an empty directory, so that the build can\n   safely make clones of repositories it depends on as _peers_ of `adversaria`.\n   Run `wrath -F` in the repository root. This will download and compile the\n   latest version of Scala, as well as all of Adversaria's dependencies.\n\n   If the build was successful, the compiled JAR files can be found in the\n   `.wrath/dist` directory.\n\n## Contributing\n\nContributors to Adversaria are welcome and encouraged. New contributors may like\nto look for issues marked\n[beginner](https://github.com/propensive/adversaria/labels/beginner).\n\nWe suggest that all contributors read the [Contributing\nGuide](/contributing.md) to make the process of contributing to Adversaria\neasier.\n\nPlease __do not__ contact project maintainers privately with questions unless\nthere is a good reason to keep them private. While it can be tempting to\nrepsond to such questions, private answers cannot be shared with a wider\naudience, and it can result in duplication of effort.\n\n## Author\n\nAdversaria was designed and developed by Jon Pretty, and commercial support and\ntraining on all aspects of Scala 3 is available from [Propensive\nO\u0026Uuml;](https://propensive.com/).\n\n\n\n## Name\n\n_Adversaria_ are miscellaneous collections of notes or _annotations_, after which the library is named.\n\nIn general, Soundness project names are always chosen with some rationale,\nhowever it is usually frivolous. Each name is chosen for more for its\n_uniqueness_ and _intrigue_ than its concision or catchiness, and there is no\nbias towards names with positive or \"nice\" meanings—since many of the libraries\nperform some quite unpleasant tasks.\n\nNames should be English words, though many are obscure or archaic, and it\nshould be noted how willingly English adopts foreign words. Names are generally\nof Greek or Latin origin, and have often arrived in English via a romance\nlanguage.\n\n## Logo\n\nThe logo is an [arobase](https://en.wikipedia.org/wiki/At_sign) or \"at-sign\", being the Scala (and Java) symbol which introduces an annotation.\n\n## License\n\nAdversaria is copyright \u0026copy; 2025 Jon Pretty \u0026 Propensive O\u0026Uuml;, and\nis made available under the [Apache 2.0 License](/license.md).\n\n","funding_links":[],"categories":[],"sub_categories":[],"project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpropensive%2Fadversaria","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fpropensive%2Fadversaria","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpropensive%2Fadversaria/lists"}