Add git hooks and setup (#2188)

Automatically `cargo clippy` and others before you commit

.hooks/pre-commit

@@ -0,0 +1,24 @@
+#/bin/sh
+
+function check {
+    prog=$1
+    shift
+    "$prog" "$@"
+    if [ $? -ne 0 ]; then
+        exit 1
+    fi
+}
+
+check cargo clippy
+
+staged_py_files=$(git diff --cached --name-only --diff-filter=ACM | grep '\.py$')
+
+if [ -n "$staged_py_files" ]; then
+    flake8_executable=$(which flake8 || which flake)
+    if [ -z "$flake8_executable" ]; then
+        echo "flake is not installed"
+        exit 1
+    else
+        check "$flake8_executable" $staged_py_files
+    fi
+fi

docs/intro.md

@@ -56,6 +56,11 @@ cargo build # Builds the compiler
 ./target/debug/calyx --help # Executes the compiler binary
 ```
 
+We recommend installing the git hooks to run linting and formatting checks before each commit:
+```shell
+/bin/sh setup_hooks.sh
+```
+
 ## Running Core Tests
 
 The core test suite tests the Calyx compiler's various passes.

setup_hooks.sh

@@ -0,0 +1,7 @@
+#/bin/sh
+
+for hook in .hooks/*; do
+    hook_name=$(basename "$hook")
+    cp "$hook" ".git/hooks/$hook_name" && chmod +x ".git/hooks/$hook_name"
+done
+echo "Done"