Add a script to automatically write the formula

.gitignore

@@ -0,0 +1,2 @@
+# Ignore assets downloaded by update script.
+*_asset

Formula/pls.rb

@@ -6,9 +6,7 @@ class Pls < Formula
   if OS.mac?
     url "https://github.com/pls-rs/pls/releases/download/v0.0.1-beta.3/pls-x86_64-apple-darwin.zip"
     sha256 "5ba90ddb239fb1d76c462ebf3b7265a16b613651e230230b3b8c8c53e4e51c48"
-  end
-
-  if OS.linux?
+  elsif OS.linux?
     url "https://github.com/pls-rs/pls/releases/download/v0.0.1-beta.3/pls-x86_64-unknown-linux-musl.zip"
     sha256 "a8e30f7475ba339494d059aea37ecca7dcde2dd1ed1ecfbada0082a6ba8b429b"
   end

Template/pls.rb.jinja

@@ -0,0 +1,29 @@
+class Pls < Formula
+  desc "Prettier and powerful ls for the pros"
+  homepage "https://pls.cli.rs/"
+  license "GPL-3.0-or-later"
+
+  if OS.mac?
+    url "{{ MAC_URL }}"
+    sha256 "{{ MAC_SHA }}"
+  elsif OS.linux?
+    url "{{ LINUX_URL }}"
+    sha256 "{{ LINUX_SHA }}"
+  end
+
+  depends_on "libgit2"
+
+  def install
+    bin.install "pls"
+  end
+
+  test do
+    linkage_with_libgit2 = (bin/"pls").dynamically_linked_libraries.any? do |dll|
+      next false unless dll.start_with?(HOMEBREW_PREFIX.to_s)
+
+      File.realpath(dll) == (Formula["libgit2"].opt_lib/shared_library("libgit2")).realpath.to_s
+    end
+
+    assert linkage_with_libgit2, "No linkage with libgit2! Cargo is likely using a vendored version."
+  end
+end

scripts/update_formula.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+REPO="pls-rs/pls"
+RELEASE=$(curl -s "https://api.github.com/repos/${REPO}/releases" | jq -r '.[0]')
+
+NAME=$(echo ${RELEASE} | jq -r '.name')
+echo "Latest release is ${NAME}."
+
+MAC_URL=$(echo ${RELEASE} | jq -r '.assets[] | select(.name | contains("apple-darwin")).browser_download_url')
+echo "Downloading macOS asset from ${MAC_URL}."
+
+curl -sL ${MAC_URL} -o mac_asset
+MAC_SHA=$(shasum -a 256 mac_asset | awk '{ print $1 }')
+echo "SHA256 for macOS asset is ${MAC_SHA}."
+
+LINUX_URL=$(echo ${RELEASE} | jq -r '.assets[] | select(.name | contains("unknown-linux-musl")).browser_download_url')
+echo "Downloading Linux asset from ${LINUX_URL}."
+
+curl -sL ${LINUX_URL} -o linux_asset
+LINUX_SHA=$(shasum -a 256 linux_asset | awk '{ print $1 }')
+echo "SHA256 for Linux asset is ${LINUX_SHA}."
+
+sed -e "s|{{ MAC_URL }}|$MAC_URL|g" \
+    -e "s|{{ MAC_SHA }}|$MAC_SHA|g" \
+    -e "s|{{ LINUX_URL }}|$LINUX_URL|g" \
+    -e "s|{{ LINUX_SHA }}|$LINUX_SHA|g" "Template/pls.rb.jinja" > "Formula/pls.rb"
+
+echo "Formula written!"