Blog Scaladoc tables

blog/_posts/2018-10-04-scaladoc-tables.md

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+---
+layout: blog-detail
+post-type: blog
+by: Janek Bogucki
+title: "Introducing Scaladoc Tables"
+---
+
+Scala 2.12.7 adds support for markdown tables in Scaladoc comments.
+
+### A Simple Example
+
+The markdown for tables follows [GitHub Flavored Markdown](https://github.github.com/gfm/) with some restrictions.
+
+This table shows all three available table elements,
+
+```
+| Trait | Implementations |
+| ---   | ---             |
+| Set   | HashSet, HashTrieSet |
+| Seq   | List, Vector, Empty  |
+| Map   | HashTrieMap, ListMap |
+```
+
+A table is comprised of,
+
+ - A header row
+ - A delimiter row
+ - Zero or more data rows
+
+This is how the above markdown renders,
+
+![Example Table 1](/resources/img/blog/scaladoc-tables/example-table-1.png)
+
+On an incidental note, there is no requirement to align header and cell markdown pipes. This is done in the examples
+to make them easier to scan.
+
+### GitHub Flavored Markdown Conformance
+
+Scaladoc tables support the [GitHub Flavored Markdown Spec Table Extension](https://github.github.com/gfm/#tables-extension-).
+
+There are some restrictions,
+
+* Every row must start and end with the pipe `|`
+* Rows markdown must start on the left edge of the Scala comment
+* The final row must be followed by a blank line
+
+These restrictions do not restrict the types of tables that can be created but do have the benefit of allowing simple Scaladoc parsing code.
+
+Picking a popular markdown flavor brings several advantages over creating yet another table markdown variation including,
+- No need to explain a new approach
+- IDEs and documentation tools can take advantage of existing markdown parsing libraries
+
+### Header Cells, Data Cells
+
+Cell content supports the standard inline styling syntax including bold, italic, monospace, underline, superscript, subscript and links.
+
+This two table example includes bold, monospace, italic, superscript and a link,
+
+```
+/**
+  * | Title | ISBN | Authors |
+  * | :---:  | ---  | --- |
+  * | '''Structured Programming''' | `0-12-200550-3` | ''Dahl, Dijkstra and Hoare'' |
+  * | '''Purely functional data structures'''^1^ | `0-521-66350-4` | ''Okasaki'' |
+  *
+  * | Note | Comment |
+  * | ---: | --- |
+  * | 1 | [[https://cambridge.org Cambridge University Press]], 1998|
+*/
+trait Bibliography
+```
+
+Markdown paid, we get this reward,
+
+![Example Table 2](/resources/img/blog/scaladoc-tables/example-table-2.png)
+
+Breaking content over several lines is not supported in GFM tables. Use a `<br/>` tag or go with HTML tables if you have needs beyond the simple tables supported by GFM.
+
+### Column Alignment
+
+Specify column alignments using hyphen and colon patterns.
+
+| Delimiter Cell Content | Alignment Type |
+| ---     | --- |
+| `---`   | Left |
+| `:---`  | Left |
+| `---:`  | Right |
+| `:---:` | Center |
+
+### Including pipe (`|`) in content.
+
+Scala 2.12.8 will support the [escaping of the cell delimiter in cell content](https://github.com/scala/scala/pull/7247) with `\|`.
+
+### More Examples
+
+For a smorgasbord of examples take a look at [examples](http://janekdb.github.io/scala/PR-7247/scala/test/scaladoc/tables/code/index.html).
+
+### Dotty and Scala 3
+
+With `dotty` now boosting its share of the development horizon it's important to place GFM into a [dottydoc](https://dotty.epfl.ch/docs/usage/dottydoc.html) and hence Scaladoc 3 context.
+
+In overview `dottydoc` supports the current Scaladoc 2.12 MediaWiki flavored markdown, but it also supports more contemporary flavors of markdown.
+
+Within the realm of table markdown `dottydoc` supports some extensions via the [flexmark-java table extension](https://github.com/vsch/flexmark-java/wiki/Tables-Extension).
+
+[flexmark-java](https://github.com/vsch/flexmark-java) allows tables to be defined using a more expressive variant of GFM table markdown. Tables you create now will have a route to being reused for `dottydoc` API documentation.
+
+### Scala 2.11 Compatibility
+
+Table markdown will not be interpreted by Scala 2.11 nor will it interfere with parsing.
+
+Content using pipes will display in the generated Scaladoc with the pipes included as literal characters. Bear this in mind if cross compiling.
+
+### How can I help?
+
+* Use Scaladoc tables
+* Share your feedback on [Discourse/Documentation](https://users.scala-lang.org/c/documentation)
+