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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 you must provide exactly one handler per alternative in the union. You
cannot omit any handlers
For example, the following expression is $_NOT valid:
Invalid: Missing ❰Right❱ handler
⇩
┌─────────────────────────────────────────────────┐
│ let handlers = { Left = Natural/even } │
│ in let union = < Left = +2 | Right : Bool > │
│ in merge handlers union : Bool │
└─────────────────────────────────────────────────┘
Note that you need to provide handlers for other alternatives even if those
alternatives are never used
You need to supply the following handlers:
↳ $txt0
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