每次执行 script.swift 都会检查是否需要重新编译，最后会执行编译后的 script.swiftc。

script.swift

/*/../usr/bin/true

source="$0"
compiled="$0"c

if [[ "$source" -nt "$compiled" ]]; then
DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer xcrun swiftc -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk -g "$source" -o "$compiled"  || exit
fi

"$compiled"

exit
*/

print("👍")