Repurpose Sign Example for Maybe Type in Documentation

[NickSeagull]

The current example function, getSign, determines if a number is positive, negative, or zero by returning one of three values: Positive, Negative, or Zero. However, this classification can be debated, as zero is often considered to have no sign at all. Given this interpretation, the example could better demonstrate the use of the Maybe type.

Proposed Change:

Modify the existing getSign function to return a Maybe Sign type, where:

• Just Positive indicates a positive number.
• Just Negative indicates a negative number.
• Nothing represents zero, reflecting that zero has no sign.

Updated Code Example:

data Sign = Positive | Negative

-- Returns Maybe Sign to reflect the absence of sign for zero
getSign :: Int -> Maybe Sign
getSign n
  | n > 0 = Just Positive
  | n < 0 = Just Negative
  | otherwise = Nothing

Benefits:

• Aligns with the mathematical interpretation that zero has no sign.
• Demonstrates a practical use case for Maybe, making it easier to understand when and why to use this type in Haskell.

Impact on Documentation:

This change would update the Sign example in the documentation to provide a clearer and more nuanced understanding of Maybe. It would serve as a concrete illustration of how to handle values that might not exist, improving the educational value of the example.

Additional Context:

This suggestion is based on the reasoning that zero lacks a positive or negative sign, making Maybe a more suitable approach for this specific use case.