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Dealing with extra parameters in recursive sumtypes #30

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MilesCranmer opened this issue May 28, 2023 · 5 comments · Fixed by #49
Closed

Dealing with extra parameters in recursive sumtypes #30

MilesCranmer opened this issue May 28, 2023 · 5 comments · Fixed by #49

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@MilesCranmer
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Hey @MasonProtter, really nice package.

Is there a way I can make a recursive SumType which uses the correct parametrized field type?

For example, say I want to make a linked list, with a separate type for the end of the list:

@sum_type LinkedList begin
    BranchNode(val::Float64, child::LinkedList)
    EndNode(val::Float64)
end

However, this LinkedList type referenced in BranchNode is actually generic and will incur type inference issues, as the sum type is parametrized:

julia> typeof(BranchNode(0.1, EndNode(0.1)))
LinkedList{8, 1, UInt8}

Is there a way I can get this same parametrization within the @sum_type macro, so that I may use it to build recursive SumTypes?

Cheers,
Miles
@MilesCranmer
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One solution would be to have the macro find all instances of the same sum type within the scope, and add additional parameters to them. So, for example,

@sum_type LinkedList{T} begin
    BranchNode(val::T, child::LinkedList{T})
    EndNode(val::T)
end

would have the referenced type expanded to

BranchNode(val::T, child::LinkedList{T,8,1,UInt8})

@MasonProtter
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Ah good point, I didn't think of that. Hmm, I'll need to think about the best way to approach this, it's actually a little tricky.

@MasonProtter MasonProtter changed the title Recursive SumType? Dealing with extra parameters in recursive sumtypes Jun 9, 2023
@mrufsvold mrufsvold mentioned this issue Jun 17, 2023
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@MilesCranmer
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Anything I can help with on this?

@MasonProtter MasonProtter mentioned this issue Jun 26, 2023
Merged
@MasonProtter
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Hey @MilesCranmer I don't think so. I've made a big overhaul going back to unions, but being smarter about some thing while handling them in #49, so there won't be any extra type parameters after that merges.

@MilesCranmer
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Nice!!

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Back to union storage MasonProtter/SumTypes.jl
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@MilesCranmer @MasonProtter