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Explanation: You can ❰merge❱ the alternatives of a union using a record with one
handler per alternative, like this:
┌─────────────────────────────────────────────────────────────────────┐
│ let union = < Left = +2 | Right : Bool > │
│ in let handlers = { Left = Natural/even, Right = λ(x : Bool) → x } │
│ in merge handlers union : Bool │
└─────────────────────────────────────────────────────────────────────┘
... but the second argument to ❰merge❱ must be a union and not some other type.
For example, the following expression is $_NOT valid:
┌──────────────────────────────────────────┐
│ let handlers = { Foo = λ(x : Bool) → x } │
│ in merge handlers True : True │
└──────────────────────────────────────────┘
⇧
Invalid: ❰True❱ isn't a union
You tried to ❰merge❱ this expression:
↳ $txt0
... which is not a union, but is actually a value of type:
↳ $txt1
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