E01077: 'def' does not exist in EK9 - define functions by name directly

What went wrong

The 'def' keyword does not exist in EK9. It is reported wherever it is written: a function declaration in a 'defines function' block, a method in a class, trait or program body ('def greet(name as String)'), or a statement ('def name()').

Worked examples

Compilable examples demonstrating this error and the correct fix:

• ek9 -q 786 (Which keywords from other languages are excluded from E...)

Rationale

EK9 defines functions by name directly without a keyword:

• Cleaner syntax without visual noise
• Function name is the first thing you see
• Similar to method definitions in classes

How to fix it

Remove 'def' and start with the function name directly. Use -> for parameters and <- for return values: 'def greet(name as String)' becomes a declaration named 'greet()' whose body starts with '-> name as String'.

See also

• E01077: 'def' not supported (EK9 uses function name directly)
• E01078: 'elif' not supported (use 'else if')
• E01079: 'None' not supported (use tri-state semantics)
• E01080: 'self' not supported (use 'this')
• E01081: list comprehensions not supported (use stream pipelines)

https://ek9.io/functions.html https://ek9.io/forAI.json#$.excludedFeatures.features[?(@.keyword=="def")]

Examples

Every example is compiled by the EK9 compiler: the first fails exactly as captioned, the others fix it.

Fails with E01077: 'def' does not exist in EK9 - define functions by name directly

#!ek9
defines module error.e01077.bad

  defines function

    def greet(name as String)
      stdout <- Stdout()
      stdout.println("Hello " + name)

Fixed: Define the function by name in a defines function block; parameters follow '->'

#!ek9
defines module error.e01077.good

  defines function

    greet()
      -> name as String
      stdout <- Stdout()
      stdout.println("Hello " + name)