EffectTalk

Defining typed errors with Data.TaggedError

Use Data.TaggedError to define your own typed error types. Tagged errors carry a _tag for pattern matching and can hold structured data (e.g. userId, message).

Unlike plain strings or Error, tagged errors are explicit in the type system and work with catchTag.

  • Use class X extends Data.TaggedError("TagName")<{ fields }> {}
  • The _tag enables catchTag("TagName", ...)
  • Add fields (e.g. message, code) for context
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