Problem with types

[lehoff]

I have define the following:

module TVJulia

@data MinuteOutcome begin
    HomeGoal
    AwayGoal
    NoGoal
    BothGoal
end

@data Score begin
    ZeroZero
    ZeroOne
    OneZero
    OneOne
    Even
    Plus(Int)
    Minus(Int)
end

# const SCORES::Vector{Score.Type} = [
#     Score.ZeroZero, Score.ZeroOne, Score.OneZero, Score.OneOne, Score.Even,
#     Score.Plus(1), Score.Plus(2), Score.Plus(3), Score.Plus(4), Score.Plus(5),
#     Score.Minus(1), Score.Minus(2), Score.Minus(3), Score.Minus(4), Score.Minus(5)]
function scores() 
    Score.Type[
        Score.ZeroZero::Score.Type, Score.ZeroOne, Score.OneZero, Score.OneOne, Score.Even,
        Score.Plus(1), Score.Plus(2), Score.Plus(3), Score.Plus(4), Score.Plus(5),
        Score.Minus(1), Score.Minus(2), Score.Minus(3), Score.Minus(4), Score.Minus(5)
    ]
end

function Base.:+(s::Score.Type, mo::MinuteOutcome.Type)
    @match mo begin
        MinuteOutcome.HomeGoal => 
            @match s begin
                Score.ZeroZero => Score.OneZero
                Score.ZeroOne  => Score.OneOne
                Score.OneZero  => Score.Plus(2)
                Score.OneOne   => Score.Plus(1)
                Score.Even     => Score.Plus(1)
                Score.Plus(n)  => Score.Plus(min(n+1, 5))
                Score.Minus(1) => Score.Even
                Score.Minus(n) => Score.Minus(n-1)
            end
        MinuteOutcome.AwayGoal =>
            @match s begin
                Score.ZeroZero => Score.ZeroOne
                Score.ZeroOne  => Score.Minus(2)
                Score.OneZero  => Score.OneOne
                Score.OneOne   => Score.Minus(1)
                Score.Even     => Score.Minus(1)
                Score.Plus(1)  => Score.Even
                Score.Plus(n)  => Score.Plus(n-1)
                Score.Minus(n) => Score.Minus(min(n+1, 5))                
            end
        MinuteOutcome.BothGoal =>
            @match s begin
                Score.ZeroZero => Score.OneOne
                Score.ZeroOne  => Score.Minus(1)
                Score.OneZero  => Score.Plus(1)
                Score.OneOne   => Score.Even
                _ => s
            end
        MinuteOutcome.NoGoal => s
    end
end

But I am running into problems - one after the other.

> TVJulia.scores()
MethodError: Cannot `convert` an object of type Type{Main.TVJulia.Score.ZeroZero} to an object of type Main.TVJulia.Score.Type

Closest candidates are:
  convert(::Type{T}, ::T) where T
   @ Base Base.jl:84
  Main.TVJulia.Score.Type(::Any)
   @ Main.TVJulia none:0


Stacktrace:
 [1] setindex!(A::Vector{Main.TVJulia.Score.Type}, x::Type, i1::Int64)
   @ Base ./array.jl:1021
 [2] (::Base.var"#114#115"{Vector{Main.TVJulia.Score.Type}})(i::Int64, v::Type)
   @ Base ./array.jl:456
 [3] afoldl(::Base.var"#114#115"{Vector{Main.TVJulia.Score.Type}}, ::Int64, ::Type, ::Type, ::Type, ::Type, ::Type, ::Main.TVJulia.Score.Type, ::Main.TVJulia.Score.Type, ::Main.TVJulia.Score.Type, ::Main.TVJulia.Score.Type, ::Main.TVJulia.Score.Type, ::Main.TVJulia.Score.Type, ::Main.TVJulia.Score.Type, ::Main.TVJulia.Score.Type, ::Main.TVJulia.Score.Type, ::Main.TVJulia.Score.Type)
   @ Base ./operators.jl:544
 [4] getindex(::Type{Main.TVJulia.Score.Type}, ::Type, ::Type, ::Type, ::Vararg{Any})
   @ Base ./array.jl:455
 [5] scores()
   @ Main.TVJulia ~/git/lehoff/TVJulia/src/TVJulia.jl:97
 [6] top-level scope
   @ In[97]:1

When I try to use my + operator I get:

> TVJulia.Score.ZeroZero + TVJulia.MinuteOutcome.HomeGoal

MethodError: no method matching +(::Type{Main.TVJulia.Score.ZeroZero}, ::Type{Main.TVJulia.MinuteOutcome.HomeGoal})

Closest candidates are:
  +(::Any, ::Any, ::Any, ::Any...)
   @ Base operators.jl:587


Stacktrace:
 [1] top-level scope
   @ In[88]:1

This leaves me rather confused.

Happy to conduct further investigations if that would be of any help.

[Roger-luo]

Unfortunately we can't have real singleton (e.g type is the same as instance) this is not supported by Julia, so you need to explicitly write the instance (otherwise that's just a variant type). I was actually thinking this, maybe we should just remove the singleton syntax.

[lehoff]

Not sure I understand what I need to do - could you give an example?

Follow up question: what would happen if I used ZeroZero() instead of ZeroZero? Can I still compare them for equality?

[Roger-luo]

You only need to use ZeroZero() in the pattern match (whenever you need to construct an instance), e.g

julia> Score.ZeroZero
Main.Score.ZeroZero

julia> Score.ZeroZero()
Main.Score.var"typeof(Score)"(Main.Score.var"##Storage#ZeroZero"())

this is what I meant there is no real singleton type, it was only a syntax sugar, ZeroZero() is the actual instance.

[Roger-luo]

actually maybe I'll just correct your script here

module TVJulia

@data MinuteOutcome begin
    HomeGoal
    AwayGoal
    NoGoal
    BothGoal
end

@data Score begin
    ZeroZero
    ZeroOne
    OneZero
    OneOne
    Even
    Plus(Int)
    Minus(Int)
end

# const SCORES::Vector{Score.Type} = [
#     Score.ZeroZero, Score.ZeroOne, Score.OneZero, Score.OneOne, Score.Even,
#     Score.Plus(1), Score.Plus(2), Score.Plus(3), Score.Plus(4), Score.Plus(5),
#     Score.Minus(1), Score.Minus(2), Score.Minus(3), Score.Minus(4), Score.Minus(5)]
function scores() 
    Score.Type[
        Score.ZeroZero(), Score.ZeroOne(), Score.OneZero(), Score.OneOne(), Score.Even(),
        Score.Plus(1), Score.Plus(2), Score.Plus(3), Score.Plus(4), Score.Plus(5),
        Score.Minus(1), Score.Minus(2), Score.Minus(3), Score.Minus(4), Score.Minus(5)
    ]
end

function Base.:+(s::Score.Type, mo::MinuteOutcome.Type)
    @match mo begin
        MinuteOutcome.HomeGoal => 
            @match s begin
                Score.ZeroZero() => Score.OneZero()
                Score.ZeroOne()  => Score.OneOne()
                Score.OneZero()  => Score.Plus(2)
                Score.OneOne()   => Score.Plus(1)
                Score.Even()     => Score.Plus(1)
                Score.Plus(n)  => Score.Plus(min(n+1, 5))
                Score.Minus(1) => Score.Even()
                Score.Minus(n) => Score.Minus(n-1)
            end
        MinuteOutcome.AwayGoal =>
            @match s begin
                Score.ZeroZero() => Score.ZeroOne()
                Score.ZeroOne()  => Score.Minus(2)
                Score.OneZero()  => Score.OneOne
                Score.OneOne()   => Score.Minus(1)
                Score.Even()     => Score.Minus(1)
                Score.Plus(1)  => Score.Even()
                Score.Plus(n)  => Score.Plus(n-1)
                Score.Minus(n) => Score.Minus(min(n+1, 5))                
            end
        MinuteOutcome.BothGoal =>
            @match s begin
                Score.ZeroZero() => Score.OneOne()
                Score.ZeroOne()  => Score.Minus(1)
                Score.OneZero()  => Score.Plus(1)
                Score.OneOne()   => Score.Even()
                _ => s
            end
        MinuteOutcome.NoGoal() => s
    end
end

[jakobjpeters]

maybe we should just remove the singleton syntax.

That would feel more consistent 👍