Statement functions

By default SQRL functions cannot be used as statements. They need to either be used in calculating a feature or a rule.

Statement functions allow you to register functions that can act as entire statements. For example you might want to implement a statement that writes out a file during SQRL execution:

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writeFile("last-username.txt", Username);

Execution of statements

By default when you start up a SQRL execution nothing is run. Calling execution.fetchFeature will start calculating that feature and any dependant ones.

Running statements uses special Statement Features such as SqrlFileStatements below. These features always evaluate to true, however their promise will only be resolved once all the statements have been run. If you want an execution to run all statements you can fetch the magic feature SqrlExecutionComplete.

Example statement definition

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const writeFileAsync = util.promisify(fs.writeFile);

registry.registerStatement(
  "SqrlFileStatements",
  async function writeFile(
    state: Execution,
    filename: string,
    contents: string
  ) {
    await fs.writeFileAsync(filename, contents);
  }
);

Statement features

By default in a SQRL execution no statements are run.

In the example above execution.fetchFeature('SqrlFileStatements') will cause all writeToFile statements to be called. By default SqrlExecutionComplete includes all the special statement features, and that is loaded before any mutations are run.