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F# / Bindings and Types

Explicit type annotations

Learn Explicit type annotations in F# through a focused explanation, a dedicated topic-specific example, an engineering boundary, and a mastery check.

10 min read • Beginner

Explicit type annotations is a focused F# lesson inside Bindings and Types. The example uses the construct named in the lesson directly rather than reusing a generic placeholder.

Trace the example from its inputs through Explicit type annotations 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-0004-01fde9fb7b.fsx
fsharp Try It Live 
let values5 = [5; 6; 7]
printfn "%d" (List.sum values5) // Explicit type annotations
Edge case / engineering note

For Explicit type annotations, 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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