My function uses return to send back a value. How do I fix it?

EK9 has no return statement. Declare the return value with <- at the top of the function, then assign to it.

BEFORE (wrong):

  calculateArea()
    -> radius as Float
    return 3.14159 * radius * radius

AFTER (fixed):

  calculateArea() as pure
    -> radius as Float
    <- rtn as Float: 3.14159 * radius * radius

The <- rtn as Float line declares a variable called rtn that IS the return value. You can assign to it with := later in the function if needed:

  findLabel()
    -> code as Integer
    <- rtn as String: "unknown"

    switch code
      case 1
        rtn := "active"
      case 2
        rtn := "inactive"

Every code path must initialise the return value. The compiler enforces this — there is no way to forget.

Example

defines module qa.gettingstarted.fixreturn

  defines function

    calculateArea() as pure
      -> radius as Float
      <- rtn as Float: 3.14159 * radius * radius

    findLabel() as pure
      -> code as Integer
      <- rtn as String: "unknown"

      switch code
        case 1
          rtn := "active"
        case 2
          rtn := "inactive"
        default
          rtn := "unknown"

  defines program

    FixReturnDemo()
      stdout <- Stdout()

      area <- calculateArea(5.0)
      stdout.println(`Area: ${area}`)

      label <- findLabel(1)
      stdout.println(`Label: ${label}`)

Common mistakes

E01072 — 'return' does not exist in EK9. Declare the return value with <- at the function top, then assign to it.

Incorrect:

    return 3.14159 * radius * radius

Correct:

    <- rtn as Float: 3.14159 * radius * radius

Other ways to ask this

Quick fix: replace return statement in EK9
EK9 has no return keyword. What do I use instead?
How do I return a value from an EK9 function?

Coming from another language?

EK9 uses declared return values instead of return statements. The compiler ensures all paths assign a value.

Keywords: declare, function, quick, fix, return