E07860: require a function or function delegate

What went wrong

This context requires a function or function delegate but one wasn't provided.

Worked examples

Compilable examples demonstrating this error and the correct fix:

• ek9 -q 857 (Why does stream split require a function or delegate?)

How to fix it

1. Provide function or delegate
2. Or use named function reference

Common causes

• Missing function argument
• Wrong type passed (value instead of function)

See also

• E07860: function delegate required (this error)
• E07870: Integer or function required

Examples

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

Fails with E07860: require a function or function delegate

#!ek9
defines module error.e07860.bad

  defines function

    doubleAll()
      <- rtn as List of Integer: List()
      doubler <- 42

      //map needs a function to apply to each item
      cat [1, 2, 3] | map with doubler > rtn

Fixed: Give map a function

#!ek9
defines module error.e07860.good

  defines function

    doubler()
      -> number as Integer
      <- rtn as Integer: number * 2

    doubleAll()
      <- rtn as List of Integer: List()
      cat [1, 2, 3] | map with doubler > rtn

Questions and answers

These Q&A entries show E07860 and its fix:

• Q857: Why does stream split require a function or delegate?