concept Option type in category functional programming

This is an excerpt from Manning's book Grokking Functional Programming MEAP V11. Login to get full access to this book.

name should be a non-empty String,

This is not a functional way! Pure functions always indicate all of the possible return values. The signature of parseShow needs to indicate that for some Strings, there is no correct TvShow.

This is an excerpt from Manning's book Functional Programming in C#: How to write better C# code. Login to get full access to this book.

Partial functions are problematic because it’s not clear what the function should do when given an input for which it can’t compute a result? The Option type offers a perfect solution to model such cases: if the function is defined for the given input, it returns a Some wrapping the result; otherwise, it returns None.

Listing 8.9. A property-based test proving that right identity holds for the Option type

[Property(Arbitrary = new[] { typeof(ArbitraryOption) })] void RightIdentityHolds(Option<object> m) => Assert.Equal( m, m.Bind(Some) );

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