Option¶

Represents a value that is either present or not present.

It is a struct, preventing you from returning null instead.

Can be used for value and reference types.

Extension Methods¶

Map - Option<T> -> Option<TR>¶

The Map extension methods allow you to transform an Option<T> to an Option<TR>.

The transformation will only occur if there is a value present.

Switch - Option<T> -> TR¶

The Switch extension methods allow you to transform an Option<T> to a TR.

You have to say what to return when the value is present and not present.

DoSwitch - Perform side-effect¶

The DoSwitch extension methods allow you to perform a side-effect on an Option<T>.

You have to say what to do when the value is present and not present.

TryGetValue - Get a value from a Dictionary¶

The TryGetValue extension methods work with dictionary.

They get the value from a dictionary as an Option<T>.

Factory - T -> Option<T>¶

There are a number of factory extension methods.

From¶

Converts a T to an Option<T>

If the value is not null, then it will be a Option<T> with the value on it.

If the value is null, then it will be a Option<T> with the value not set.

None¶

Returns a Option<T> with the value not set.

ToOption¶

Converts a T to an Option<T>

If the value is not null, then it will be a Option<T> with the value on it.

If the value is null, then it will be a Option<T> with the value not set.

Implicit conversion¶

There is an implicit conversion in place. So if your method returns an T, then it will be automatically converted to an Option<T>.

OrElse and GetValueOrDefault¶

The OrElse extension methods are good when you have a precedence order.

The GetValueOrDefault extension methods are used to as a terminating method and will take you out if an Option, returning the default value provided if the Option has no value.

TryParse¶

There are a lot of TryParse extension methods provided, for a lot of the built-in framework types:

LINQ¶

TryElementAt¶

TryFirst¶

TryLast¶

TrySingle¶

Enumerable<Option<T>>¶

Choose¶

Map¶

MapSwitch¶

Pick¶

Interop with Nullable¶

For structs there is interop with Nullable

Nullable -> Option¶

Use the ToOption extension method.

Option -> Nullable¶

Use the ToNullable extension method.

Interop with Result¶

Option -> Result¶

You can move between an Option and a Result using the 'ToResult' extension method. You just need to provide the error if the Option is not present.

Result -> Option¶

This is not supported as it would result in the loss of the error context.