improve plugin section in README (#4789)

* improve plugin section in README

* add semparse to default plugins

* clean up

CHANGELOG.md

@@ -8,6 +8,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- Adds [`allennlp-semparse`](https://github.com/allenai/allennlp-semparse) as an official, default plugin.
+
 ### Fixed
 
 - `GumbelSampler` now sorts the beams by their true log prob.

README.md

@@ -65,12 +65,46 @@ And others on the [AI2 AllenNLP blog](https://medium.com/ai2-blog/allennlp/home)
 AllenNLP supports loading "plugins" dynamically. A plugin is just a Python package that
 provides custom registered classes or additional `allennlp` subcommands.
 
-There are several official [default plugins](https://docs.allennlp.org/master/api/common/plugins/#default_plugins) and an ecosystem of third-party plugins, including:
+There is ecosystem of open source plugins, some of which are maintained by the AllenNLP
+team here at AI2, and some of which are maintained by the broader community.
 
-* [allennlp-optuna](https://github.com/himkt/allennlp-optuna)
+<table>
+<tr>
+    <td><b> Plugin </b></td>
+    <td><b> Maintainer </b></td>
+    <td><b> CLI </b></td>
+    <td><b> Description </b></td>
+</tr>
+<tr>
+    <td> <a href="https://github.com/allenai/allennlp-models"><b>allennlp-models</b></a> </td>
+    <td> AI2 </td>
+    <td> No </td>
+    <td> A collection of state-of-the-art models </td>
+</tr>
+<tr>
+    <td> <a href="https://github.com/allenai/allennlp-semparse"><b>allennlp-semparse</b></a> </td>
+    <td> AI2 </td>
+    <td> No </td>
+    <td> A framework for building semantic parsers </td>
+</tr>
+<tr>
+    <td> <a href="https://github.com/allenai/allennlp-server"><b>allennlp-server</b></a> </td>
+    <td> AI2 </td>
+    <td> Yes </td>
+    <td> A simple demo server for serving models </td>
+</tr>
+<tr>
+    <td> <a href="https://github.com/himkt/allennlp-optuna"><b>allennlp-optuna</b></a> </td>
+    <td> <a href="https://himkt.github.io/profile/">Makoto Hiramatsu</a> </td>
+    <td> Yes </td>
+    <td> <a href="https://optuna.org/">Optuna</a> integration for hyperparameter optimization </td>
+</tr>
+</table>
 
-In order for AllenNLP to find personal or third-party plugins, you have to create either a local plugins file named `.allennlp_plugins`
-in the directory where the `allennlp` command is run, or a global plugins file at `~/.allennlp/plugins`.
+AllenNLP will automatically find any official AI2-maintained plugins that you have installed,
+but for AllenNLP to find personal or third-party plugins you've installed,
+you also have to create either a local plugins file named `.allennlp_plugins`
+in the directory where you run the `allennlp` command, or a global plugins file at `~/.allennlp/plugins`.
 The file should list the plugin modules that you want to be loaded, one per line.
 
 To test that your plugins can be found and imported by AllenNLP, you can run the `allennlp test-install` command.
@@ -84,31 +118,31 @@ to distribute as a plugin, see the [subcommand API docs](https://docs.allennlp.o
 <table>
 <tr>
     <td><b> allennlp </b></td>
-    <td> an open-source NLP research library, built on PyTorch </td>
+    <td> An open-source NLP research library, built on PyTorch </td>
 </tr>
 <tr>
     <td><b> allennlp.commands </b></td>
-    <td> functionality for a CLI and web service </td>
+    <td> Functionality for the CLI </td>
 </tr>
 <tr>
-    <td><b> allennlp.data </b></td>
-    <td> a data processing module for loading datasets and encoding strings as integers for representation in matrices </td>
+    <td><b> allennlp.common </b></td>
+    <td> Utility modules that are used across the library </td>
 </tr>
 <tr>
-    <td><b> allennlp.models </b></td>
-    <td> a collection of state-of-the-art models </td>
+    <td><b> allennlp.data </b></td>
+    <td> A data processing module for loading datasets and encoding strings as integers for representation in matrices </td>
 </tr>
 <tr>
     <td><b> allennlp.modules </b></td>
-    <td> a collection of PyTorch modules for use with text </td>
+    <td> A collection of PyTorch modules for use with text </td>
 </tr>
 <tr>
     <td><b> allennlp.nn </b></td>
-    <td> tensor utility functions, such as initializers and activation functions </td>
+    <td> Tensor utility functions, such as initializers and activation functions </td>
 </tr>
 <tr>
     <td><b> allennlp.training </b></td>
-    <td> functionality for training models </td>
+    <td> Functionality for training models </td>
 </tr>
 </table>
 

allennlp/common/plugins.py

@@ -33,7 +33,7 @@
 The global plugins file will be found here.
 """
 
-DEFAULT_PLUGINS = ("allennlp_models", "allennlp_server")
+DEFAULT_PLUGINS = ("allennlp_models", "allennlp_semparse", "allennlp_server")
 """
 Default plugins do not need to be declared in a plugins file. They will always
 be imported when they are installed in the current Python environment.