Created
February 10, 2014 12:24
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Gotta be a better way. Also, PLens feels weird with the setter being an Option (compared to Control.Lens.Prism, at least).
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| def eitherPLens[X,A,B]( | |
| lensLeft: X @?> A , | |
| lensRight: X @?> B | |
| ): X @?> (A \/ B) = PLens.plensg( | |
| x => Some( | |
| _.fold( lensLeft.setOr( x , _ , x ), lensRight.setOr( x , _ , x) ) | |
| ), | |
| x => lensLeft.get( x ).map( -\/[A](_) ).orElse( | |
| lensRight.get( x ).map( \/-[B](_) ) | |
| ) | |
| ) |
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