[CDEC-383] Add stylish-haskell to nix and CI

Author: ruhatch

.buildkite/pipeline.yml

@@ -4,6 +4,11 @@ steps:
     agents:
       system: x86_64-linux
 
+  - label: 'stylish-haskell'
+    command: 'scripts/ci/nix-shell.sh --run scripts/check-stylish.sh'
+    agents:
+      system: x86_64-linux
+
   - label: 'stack2nix'
     command: 'scripts/ci/nix-shell.sh -p cabal2nix stack cabal-install ghc moreutils expect -Q -j 4 --run scripts/check-stack2nix.sh'
     agents:

.stylish-haskell.yaml

@@ -63,7 +63,7 @@ steps:
       #   >     (concat, foldl, foldr, head, init, last, length)
       #
       # Default: after_alias
-      list_align: after_alias
+      list_align: with_module_name
 
       # Right-pad the module names to align imports in a group:
       #
@@ -198,7 +198,7 @@ steps:
 # Note: we tend to write code which fits into 80 characters, in some cases
 # 100 is acceptable. For imports we always permit 100 characters because it
 # decreases verbosity of diffs and makes merging easier.
-columns: 100
+columns: 80
 
 # By default, line endings are converted according to the OS. You can override
 # preferred format here.

pkgs/default.nix

@@ -75842,6 +75842,75 @@ homepage = "http://github.com/ekmett/structs/";
 description = "Strict GC'd imperative object-oriented programming with cheap pointers";
 license = stdenv.lib.licenses.bsd3;
 
+}) {};
+"stylish-haskell" = callPackage
+({
+  mkDerivation
+, aeson
+, base
+, bytestring
+, containers
+, directory
+, fetchgit
+, file-embed
+, filepath
+, haskell-src-exts
+, mtl
+, optparse-applicative
+, semigroups
+, stdenv
+, strict
+, syb
+, yaml
+}:
+mkDerivation {
+
+pname = "stylish-haskell";
+version = "0.9.2.0";
+src = fetchgit {
+
+url = "https://github.com/input-output-hk/stylish-haskell.git";
+sha256 = "0d6ylb07gxv050fpzc6siwxj8c7j1pkcry5zyzimv0xwn1wf6rfy";
+rev = "ecfd3b307d8d13a6d12aff03055f25a39a17e182";
+
+};
+isLibrary = true;
+isExecutable = true;
+libraryHaskellDepends = [
+aeson
+base
+bytestring
+containers
+directory
+file-embed
+filepath
+haskell-src-exts
+mtl
+semigroups
+syb
+yaml
+];
+executableHaskellDepends = [
+aeson
+base
+bytestring
+containers
+directory
+file-embed
+filepath
+haskell-src-exts
+mtl
+optparse-applicative
+strict
+syb
+yaml
+];
+doHaddock = false;
+doCheck = false;
+homepage = "https://github.com/jaspervdj/stylish-haskell";
+description = "Haskell code prettifier";
+license = stdenv.lib.licenses.bsd3;
+
 }) {};
 "sum-type-boilerplate" = callPackage
 ({

scripts/check-stylish.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+
+# check and warn if commits don't conform to stylish-haskell
+
+set -xe
+
+fail_stylish_check() {
+  # The '-w' option for 'git diff' is used because in some builds
+  # (i.e. https://buildkite.com/input-output-hk/cardano-sl/builds/976#0fb162df-8f9b-42d7-9ca7-608a9ea06d4d)
+  # the patch to 'default.nix' only suggests that whitespaces be added
+  # (see https://gist.github.com/anonymous/f52dbb040db16034d303e27056a0a48e), without
+  # which the build fails in the 'stack2nix' step.
+  git diff -w --text > /tmp/stylish.patch
+  buildkite-agent artifact upload /tmp/stylish.patch --job "$BUILDKITE_JOB_ID"
+  echo "ERROR: you need to (run ./scripts/haskell/stylish-last-10.sh or apply the patch in the buildkite artifact) and commit the changes" >&2
+  exit 1
+}
+
+# Get relative path to script directory
+haskellScriptDir=$(dirname -- "$(readlink -f -- "${BASH_SOURCE[0]}")")/haskell/
+
+# shellcheck source=/dev/null
+source "${haskellScriptDir}stylish-last-10.sh"
+
+
+git diff -w --text --exit-code || fail_stylish_check

scripts/haskell/shell-with-stylish.nix

@@ -0,0 +1,4 @@
+let
+ cardanoPkgs = import ../../. {};
+ pkgs = import ((import ../../lib.nix).fetchNixPkgs) { };
+in pkgs.runCommand "name" { buildInputs = [ cardanoPkgs.stylish-haskell ]; } ""

scripts/haskell/stylish-last-10.sh

@@ -0,0 +1,5 @@
+nix-shell ${haskellScriptDir}shell-with-stylish.nix --run "\
+    git diff --diff-filter=AMR --name-only -r HEAD~10 |\
+    grep '.hs$' |\
+    xargs -I '{}' realpath --relative-to=. $(git rev-parse --show-toplevel)/'{}' |\
+    xargs -L 1 stylish-haskell -i"

stack.yaml

@@ -141,6 +141,12 @@ packages:
     commit: e4e879abca99d0d56015765859fb37af59a81dbb
   extra-dep: true
 
+# Add custom stylish-haskell while waiting for PR upstream: https://github.com/jaspervdj/stylish-haskell/pull/214
+- location:
+    git: https://github.com/input-output-hk/stylish-haskell.git
+    commit: ecfd3b307d8d13a6d12aff03055f25a39a17e182
+  extra-dep: true
+
 nix:
   shell-file: shell.nix