Index - U
| uncurry | Air.Env, Air |
| undefined | Air.Env, Air |
| unique | Air.Light, Air.Env, Air |
| unlines | Air.Env, Air |
| until | Air.Env, Air |
| unwords | Air.Env, Air |
| unzip | Air.Env, Air |
| unzip3 | Air.Env, Air |
| upper | Air.Light, Air.Env, Air |
| upto | Air.Light, Air.Env, Air |
| userError | Air.Env, Air |