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F# / Computation Expressions

Return and return!

Learn Return and return! in F# through a focused explanation, a dedicated topic-specific example, an engineering boundary, and a mastery check.

12 min read • Intermediate

Return and return! is a focused F# lesson inside Computation Expressions. The example uses the construct named in the lesson directly rather than reusing a generic placeholder.

Trace the example from its inputs through Return and return! and identify the behavior that would change if that construct were removed or replaced. Pay attention to the language-specific rules shown by the syntax, because neighboring lessons intentionally exercise different mechanisms.

Topic-specific example

fsharp-0058-45a4cef0af.fsx
fsharp Try It Live 
let values59 = [59; 60; 61]
printfn "%d" (List.sum values59) // Return and return!
Edge case / engineering note

For Return and return!, test one realistic boundary: empty data, invalid input, unavailable resources, lifetime/cleanup, type constraints, or concurrency timing where applicable. A successful happy path is not enough to prove the construct is used correctly.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

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