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Composing Getter & Optional returns lists #4

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kenbot opened this issue Jan 24, 2017 · 1 comment
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Composing Getter & Optional returns lists #4

kenbot opened this issue Jan 24, 2017 · 1 comment
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kenbot commented Jan 24, 2017 •
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get"$myObj.$lens.$optional" returns an Option, but get"$myObj.$getter.$optional" returns a List. This is because no "Fold1" exists, and a "Fold" is performed instead. This is surprising behaviour.

We can simulate the expected behaviour by tracking Folds that definitely only have 0-1 elements, and generating a .headOption on the end afterwards.

Something like:

case class Fold(notMulti: Boolean) extends OpticType

See optics-dev/Monocle#484
@kenbot kenbot added this to the 1.0 milestone Jan 24, 2017
@kenbot kenbot added the bug label Jan 24, 2017
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kenbot commented Feb 15, 2017

"Fold1" added to OpticTypes, with appropriate composition rules.

@kenbot kenbot closed this as completed Feb 15, 2017
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