Don't simplify keywords to nil (mentat-collective#131)

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## [unreleased]
 
+- #131 fixes accidental simplification of keywords to `nil`.
+
 ## [0.30.0]
 
 - #126:

DEVELOPING.md

@@ -0,0 +1,74 @@
+## Dev Dependencies
+
+- [node.js](https://nodejs.org/en/)
+- The [clojure command line tool](https://clojure.org/guides/install_clojure)
+- [Babashka](https://github.com/babashka/babashka#installation)
+
+## Github Pages, Docs Notebook
+
+The project's [Github Pages site](https://emmy.mentat.org) hosts an
+interactive [Clerk](https://github.com/nextjournal/clerk) notebook demonstrating
+the library's use.
+
+### Local Notebook Dev
+
+Start a Clojure process however you like, and run `(user/serve!)` to run the
+Clerk server. This command should open up `localhost:7777`.
+
+Alternatively, run
+
+```sh
+bb clerk-watch
+```
+
+### Static Build
+
+To test the static build locally:
+
+```
+bb publish-local
+```
+
+This will generate the static site in `public/build`, start a development http
+server and open up a browser window (http://127.0.0.1:8080/) with the production
+build of the documentation notebook.
+
+### GitHub Pages
+
+To build and release to Github Pages:
+
+```
+bb release-gh-pages
+```
+
+This will ship the site to https://emmy.mentat.org.
+
+## Publishing to Clojars
+
+The template for the project's `pom.xml` lives at
+[`template/pom.xml`](https://github.com/mentat-collective/emmy/blob/main/template/pom.xml).
+
+To create a new release:
+
+- Update the version in
+  [resources/EMMY_VERSION](https://github.com/mentat-collective/emmy/blob/main/resources/EMMY_VERSION)
+- Make a new [Github
+  Release](https://github.com/mentat-collective/emmy/releases) with tag
+  `v<the-new-version>`.
+
+Submitting the release will create the new tag and trigger the following
+command:
+
+```
+bb release
+```
+
+The new release will appear on Clojars.
+
+## Linting
+
+Code is linted with [`clj-kondo`](https://github.com/clj-kondo/clj-kondo):
+
+```
+bb lint
+```

README.md

@@ -206,7 +206,14 @@ documentation, you'll need to install
 - The [Clojure command line tool](https://clojure.org/guides/install_clojure)
 - [Babashka](https://github.com/babashka/babashka#installation)
 
-Once this is done, run this command:
+Next, clone the repository:
+
+```bash
+git clone [email protected]:mentat-collective/emmy.git
+cd emmy
+```
+
+Run this command in the cloned repository:
 
 ```sh
 bb clerk-watch

src/emmy/generic.cljc

@@ -14,7 +14,8 @@
   (:refer-clojure :exclude [/ + - * divide infinite? abs])
   (:require [emmy.util :as u]
             [emmy.util.def :refer [defgeneric]]
-            [emmy.value :as v]))
+            [emmy.value :as v])
+  #?(:clj (:import (clojure.lang Keyword))))
 
 ;; ## Generic Numerics
 ;;
@@ -1015,6 +1016,11 @@ defaults to `ln((1 + sqrt(1+x^2)) / x)`."
 (defgeneric simplify 1)
 (defmethod simplify :default [a] a)
 
+;; `defgeneric` installs a metadata-lookup handler for keywords by default; in
+;; this case, we want to override that feature so that keywords simplify to
+;; themselves.
+(defmethod simplify [#?(:clj Keyword :cljs 'cljs.core/Keyword)] [a] a)
+
 ;; This call registers a symbol for any non-multimethod we care about. These
 ;; will be returned instead of the actual function body when the user
 ;; calls `(v/freeze fn)`, for example.

test/emmy/generic_test.cljc

@@ -146,6 +146,14 @@
             (is (= x (g/divide x 1)) "dividing by one a single time returns the input")
             (is (= x (g/divide x 1 1 1 1.0 1)) "dividing by 1 returns the input")))
 
+(deftest simplify-tests
+  (checking "g/simplify" 100 [k gen/keyword]
+            (is (= k (g/simplify k)) "keywords simplify to themselves."))
+
+  (is (= [:div "cake"]
+         (g/simplify [:div "cake"]))
+      "Keywords simplify to themselves inside of nested structures"))
+
 (defn ^:private is* [eq actual expected]
   (is (eq actual expected)
       #?(:clj (format "expected: %s\n  actual: %s"