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as Prism that performs a downcast #1052

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kenbot opened this issue Feb 11, 2021 · 1 comment
Closed

as Prism that performs a downcast #1052

kenbot opened this issue Feb 11, 2021 · 1 comment
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3.x Next major version

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@kenbot
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kenbot commented Feb 11, 2021 •
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Something like

def as[Source, Target <: Source]: Prism[Source, Target] = {
  Prism[Source, Target](
    source => if (source.isInstanceOf[Target]) Some(source.asInstanceOf[Target]) 
              else None)(
    target => target.asInstanceOf[Source])
}

Also add syntax extension methods on to the optics, in the style of each, some, index, etc. Also, on to the ApplyXXX versions.

It should commute with the Focus macro such that Focus[Foo](_.bar.as[Baz]) == Focus[Foo](_.baz).as[Baz]
@kenbot kenbot added the 3.x Next major version label Feb 11, 2021
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kenbot commented Mar 5, 2021

Resolved by #1110

@kenbot kenbot closed this as completed Mar 5, 2021
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