Loon Playground

Try Loon in your browser — no installation required.

playground.loon
Editor
 1module auth;
 2
 3fn authenticate(
 4  username: String,
 5  password: Sensitive<String>
 6) -> [IO] Bool {
 7  // Check credentials against the database
 8  let valid = do check_password(username, password);
 9
10  // Log the attempt for auditing
11  do print("Login: user=" + username
12    + " password=" + password);
13
14  valid
15}
Compiler Output
error[E301]: cannot log Sensitive value
  --> playground.loon:12:22
   |
12 |     + " password=" + password);
   |                      ^^^^^^^^
   |
   = password: Sensitive<String>
   = logging Sensitive data is prohibited
   = hint: use redact(password) to log a
     masked representation

Compilation failed: 1 error

The playground is under development. Loon compiles to WebAssembly, which makes browser execution viable.

Try Loon locally

In the meantime, you can install Loon and try it on your machine.

$ curl -fsSL https://loonlang.org/install.sh | sh

Getting Started Guide