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guarded()

guarded<In, Out>(fn, check): (input) => Result<Out, string>

Guarded proxy - checks access before calling the function. The check returns true to allow, or a rejection reason string to deny. Returns a zygos Result: Ok(output) if allowed, Err(reason) if denied.

Type Parameters​

In: In​

The input type

Out: Out​

The output type

Parameters​

fn: (input) => Out​

The function to guard

check: (input) => string | true​

Access check. Return true to allow, or a string reason to deny.

Returns​

A proxy returning Result<Out, string>

Since​

2.4.0

Example​

const deleteUser = guarded(
  (id: string) => db.delete(id),
  (id) => id !== "admin" ? true : "Cannot delete admin user",
);

deleteUser("user-1"); // Ok(void)
deleteUser("admin");  // Err("Cannot delete admin user")