Printing values
Motoko uses Debug.print to output text to the terminal or a canister's log depending on execution context.
It takes a Text value and returns ().
() is the empty tuple and represents a token or trivial return value.
import Debug "mo:base/Debug";
Debug.print("Hello, world!");
For debugging purposes, debug_show converts most Motoko types into Text. The operator handles most types well, but may not work with cyclic data structures or types containing functions or type parameters.
import Debug "mo:base/Debug";
Debug.print(debug_show {life = 42} ); // "{life = 42}"
Functions like Debug.print("Hello, World!") are considered impure functions because they cause a side effect by printing to the console or log.
In contrast, pure functions return values that do not modify output or have other side effects like sending messages. For example Nat.toText(42) is pure because it always returns "42" with no other effect.
Resources
