Effect CommunityEC
Effect Community•3y ago•
31 replies
Wix

Issue with Creating Union Types in TypeScript

Here's an odd question. I often create my types like this 
export interface CancelledChildRecurrenceEvent
  extends S.Schema.To<typeof CancelledChildRecurrenceEventWithDiscriminant> {}
So, I get the interface name instead of type structure in IDEs like VSCode. The problem is S.union is obviously unaware of the interface and only uses the type. I find myself creating union types that are a union of the interfaces above rather than using S.Schema.To<typeof MyUnion> but then I frequently have to map my effects with .map(e => e as MyUnion) so it uses the handrolled union type. Here is a small example of what I mean: 
export interface MyTypeA
  extends S.Schema.To<typeof MyTypeA> {}
export interface MyTypeB
  extends S.Schema.To<typeof MyTypeB> {}

export const MyType = S.union(
  MyTypeA,
  MyTypeB
);

export type MyType = MyTypeA | MyTypeB

S.parseSync(MyType)(bleh).pipe(Effect.map(e => e as MyType))


Does anyone know a more elegant way to do this? Either some VSCode switch to use type names instead of their structure or an easy way for union to use my other interface? Thanks!
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