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Discussion on: Introduction to composable optics with monocle-ts

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Mike Solomon

Really cool stuff! One way that I've blended io-ts and monole-ts together is the use of the .is function in io-ts to replicate pattern matching in Haskell or OCaml. That helps especially in Prisms. So, for example...

new Prism<string | integer, string>(a => t.string.is(a) ? some(a) : none, s => s)
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Here, is is a primitive type of pattern matching that does the job both at runtime and at compile time (this is compile safe in typescript).