Why does EK9 require named arguments for 4+ parameters?

← Code Quality · Ref: Q817

EK9 requires named arguments when a call passes 4 or more positional arguments. Beyond 3 arguments, the 3rd and 4th are routinely confused.

THE RULE

3 or fewer positional arguments are fine:

  connect(host, port, timeout)       // OK: 3 args

4 or more trigger E11062:

  connect(host, port, timeout, retries)  // ERROR: use named

THE FIX

Use named arguments (EK9 requires all-or-nothing naming):

  connect(host: host, port: port, timeout: timeout, retries: retries)

WHY THIS MATTERS

Miller's Law: humans can track 7 +/- 2 items. At 4+ parameters, positional confusion causes bugs that are invisible at the call site. Named arguments make every parameter's purpose visible.

See Q694 for named argument patterns. See Q816 for Boolean argument naming.

Example

defines module qa.quality.many.args

  defines function

    scheduleJob()
      ->
        jobName as String
        path as String
        retries as Integer
        interval as Integer
      stdout <- Stdout()
      stdout.println(`Scheduled ${jobName} at ${path} retries=${retries} interval=${interval}`)

  defines program

    ManyArgsDemo()
      stdout <- Stdout()

      // === CORRECT: named arguments for 4+ parameters ===
      scheduleJob(jobName: "backup", path: "/data", retries: 3, interval: 60)

      // === CORRECT: 3 or fewer positional is fine ===
      stdout.println("Three args or fewer: no naming required")

Common mistakes

E11062 — 4 positional arguments exceed the readability threshold. Use named arguments so each parameter's purpose is clear at the call site. See ek9 -h E11062 for details.

Incorrect:

      scheduleJob("backup", "/data", 3, 60)

Correct:

      scheduleJob(jobName: "backup", path: "/data", retries: 3, interval: 60)

Coming from another language?

Java: no enforcement. Python: PEP 8 recommends keyword args for clarity. Swift: requires argument labels by default. Kotlin: supports named args. EK9: 4+ positional args = compile error.

Keywords: E11062, arguments, positional, readability, quality, many, parameters, named