Crystal: unexpected ',' in type

[Blacksmoke16]

module Test
  class Foo; end
  class Bar; end

  TYPES = {
    Foo => [] of Symbol,
    Bar => [] of Symbol
  }
end

https://play.crystal-lang.org/#/r/5avh

Syntax error in eval:6: unexpected ',' in type (use parentheses to disambiguate)

Only happens when having the comma on an empty array of T

[asterite]

You have to do what the error message tells you :-)

module Test
  class Foo; end
  class Bar; end

  TYPES = {
    Foo => ([] of Symbol),
    Bar => ([] of Symbol)
  }
end

The reason of the error is that Symbol, Bar could be the start of a Proc type.

[j8r]

Or use the classic syntax to create a new class instance:

module Test
  class Foo; end
  class Bar; end

  TYPES = {
    Foo => Array(Symbol).new,
    Bar => Array(Symbol).new
  }
end

[Blacksmoke16]

@asterite @j8r Well now the new problem is i get:

undefined macro method 'Call#map'

    CrSerializer::Assertions::NotNil => Array(Symbol).new,

and

undefined macro method 'Expressions#map'

    CrSerializer::Assertions::NotNil => ([] of Symbol),

Since im iterating over the key/values (extra code removed for simplicity), and wanting to map the values in the array. tl;dr of this is im using it to new up classes that correspond with the name of the annotation.

        {% for ivar in @type.instance_vars %}
          {% for t, v in CrSerializer::Assertions::TYPES %}
            {% ann = ivar.annotation(t.resolve) %}
              {% if ann %}
                {{v.map { |f| ann[f] }.join(',').id}}
              {% end %}
          {% end %}
        {% end %}

Ideally this would be a lot cleaner if you could iterate over all the annotations on an ivar, and iterate on keys of the annotation, but that would prob be best for another issue.

[Blacksmoke16]

For now i guess i'll just add a dummy var to the array and just do nothing with it in the initializer.

[Blacksmoke16]

For future reference, solution was to do {% v = v.expressions[0] if v.is_a?(Expressions) %} to get the actual value of the expression if it was one.