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Haskell / Values and Types

Maybe values

Learn Maybe values in Haskell through a focused explanation, a dedicated topic-specific example, an engineering boundary, and a mastery check.

10 min read • Beginner

Maybe values is a focused Haskell lesson inside Values 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 Maybe values 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

haskell-0009-5a1de9b88c.hs
haskell Try It Live 
discount :: Maybe Int -> Int
discount Nothing = 0
discount (Just n) = n

main = print (discount (Just 15))
Edge case / engineering note

For Maybe values, 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

Maybe values Mastery Check →
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