# Debug
Utility functions for debugging.

Import from the base library to use this module.
```motoko name=import
import Debug "mo:base/Debug";
```

## Function `print`
``` motoko no-repl
func print(text : Text)
```

Prints `text` to output stream.

NOTE: The output is placed in the replica log. When running on mainnet,
this function has no effect.

```motoko include=import
Debug.print "Hello New World!";
Debug.print(debug_show(4)) // Often used with `debug_show` to convert values to Text
```

## Function `trap`
``` motoko no-repl
func trap(errorMessage : Text) : None
```

`trap(t)` traps execution with a user-provided diagnostic message.

The caller of a future whose execution called `trap(t)` will
observe the trap as an `Error` value, thrown at `await`, with code
`#canister_error` and message `m`. Here `m` is a more descriptive `Text`
message derived from the provided `t`. See example for more details.

NOTE: Other execution environments that cannot handle traps may only
propagate the trap and terminate execution, with or without some
descriptive message.

```motoko
import Debug "mo:base/Debug";
import Error "mo:base/Error";

actor {
  func fail() : async () {
    Debug.trap("user provided error message");
  };

  public func foo() : async () {
    try {
      await fail();
    } catch e {
      let code = Error.code(e); // evaluates to #canister_error
      let message = Error.message(e); // contains user provided error message
    }
  };
}
```