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F#·F# essentials

Discriminated unions

Unions model a closed set of cases with optional data.

Intermediate 10 min read Lesson 4 of 150 Challenge included
What you will be able to do
  • Define with type X = A | B.
  • Match all cases.
  • Use records for named fields.

In plain English

Unions model a closed set of cases with optional data.

  • Define with type X = A | B.
  • Match all cases.
  • Use records for named fields.
unions.fsxFSHARP
type Result =
    | Ok of string
    | Error of string

let render result =
    match result with
    | Ok value -> value
    | Error message -> message

printfn "%s" (render (Ok "ready"))
Your turn

Explain it back

Easy

Answer from memory: What is a discriminated union?

TEXT · starter
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What is a discriminated union?

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Lesson 4 of 150 · 0% of course