From dbc3aa28c4ea71a6a6fce87f0bdb35717c472931 Mon Sep 17 00:00:00 2001
From: Remo <59358383+monacoremo@users.noreply.github.com>
Date: Mon, 27 Apr 2020 22:04:50 +0200
Subject: [PATCH] Add scripts for linting and styling with all dependencies
 managed by Nix (#1501)

* Integrate the style and lint dependencies with Nix

* Add documentation on the nix styling scripts.
---
 default.nix   |  6 ++++++
 nix/README.md | 14 ++++++++++++++
 nix/lint.nix  | 12 ++++++++++++
 nix/style.nix | 37 +++++++++++++++++++++++++++++++++++++
 shell.nix     |  2 ++
 5 files changed, 71 insertions(+)
 create mode 100644 nix/lint.nix
 create mode 100644 nix/style.nix

diff --git a/default.nix b/default.nix
index 1ef1189e8..1af82296a 100644
--- a/default.nix
+++ b/default.nix
@@ -72,4 +72,10 @@ rec {
         inherit postgresqlVersions;
         postgrestBuildEnv = env;
       };
+
+  style =
+    pkgs.callPackage nix/style.nix {};
+
+  lint =
+    pkgs.callPackage nix/lint.nix {};
 }
diff --git a/nix/README.md b/nix/README.md
index fe24feedc..86d3de901 100644
--- a/nix/README.md
+++ b/nix/README.md
@@ -61,6 +61,20 @@ nix-shell --run postgrest-test-spec-postgresql-9.5.21
 
 ```
 
+## Linting and styling code
+
+The nix-shell also contains scripts for linting and styling the PostgREST
+source code:
+
+```bash
+# Linting
+nix-shell --run postgrest-lint
+
+# Styling / auto-formatting code
+nix-shell --run postgrest-style
+
+```
+
 ## Tour
 
 The following is not required for working on PostgREST with Nix, but it will
diff --git a/nix/lint.nix b/nix/lint.nix
new file mode 100644
index 000000000..e498c03fb
--- /dev/null
+++ b/nix/lint.nix
@@ -0,0 +1,12 @@
+{ writeShellScriptBin, git, silver-searcher, hlint }:
+
+writeShellScriptBin "postgrest-lint"
+  ''
+    set -euo pipefail
+
+    rootdir="$(${git}/bin/git rev-parse --show-toplevel)"
+
+    # Lint Haskell files
+    ${silver-searcher}/bin/ag -l -g '\.l?hs$' "$rootdir" \
+      | xargs ${hlint}/bin/hlint -X QuasiQuotes -X NoPatternSynonyms
+  ''
diff --git a/nix/style.nix b/nix/style.nix
new file mode 100644
index 000000000..a8e4f5735
--- /dev/null
+++ b/nix/style.nix
@@ -0,0 +1,37 @@
+{ writeShellScriptBin
+, git
+, nixpkgs-fmt
+, silver-searcher
+, stylish-haskell
+, buildEnv
+}:
+let
+  style =
+    writeShellScriptBin "postgrest-style"
+      ''
+        set -euo pipefail
+
+        rootdir="$(${git}/bin/git rev-parse --show-toplevel)"
+
+        # Format Nix files
+        ${nixpkgs-fmt}/bin/nixpkgs-fmt "$rootdir" > /dev/null 2> /dev/null
+
+        # Format Haskell files
+        ${silver-searcher}/bin/ag -l -g '\.l?hs$' "$rootdir" \
+          | xargs ${stylish-haskell}/bin/stylish-haskell -i
+      '';
+
+  check =
+    writeShellScriptBin "postgrest-style-check"
+      ''
+        set -euo pipefail
+
+        ${style}/bin/${style.name}
+
+        ${git}/bin/git diff-index --exit-code HEAD -- '*.hs' '*.lhs' '*.nix'
+      '';
+in
+buildEnv {
+  name = "postgrest-style";
+  paths = [ style check ];
+}
diff --git a/shell.nix b/shell.nix
index 0c89b90a7..5d2723330 100644
--- a/shell.nix
+++ b/shell.nix
@@ -9,6 +9,8 @@ pkgs.lib.overrideDerivation env (
         pkgs.postgresql
         nixpkgsUpgrade
         tests
+        style
+        lint
       ];
 
     shellHook =