Class MaybeLinqExtensions

Namespace

Trellis

Assembly

Trellis.Results.dll

Provides LINQ query expression support for Maybe types, enabling C# query syntax for optional value composition.

public static class MaybeLinqExtensions

Inheritance

object

MaybeLinqExtensions

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Examples

// Composing multiple optional values with LINQ query syntax
Maybe<FullName> fullName =
    from first in firstName
    from last in lastName
    select new FullName(first, last);

// Chaining optional lookups
Maybe<Email> managerEmail =
    from user in users.FindById(userId)
    from manager in users.FindById(user.ManagerId)
    from email in manager.Email
    select email;

Remarks

These extension methods allow you to use LINQ query syntax (from, select) with Maybe types, making functional composition of optional values more readable.

The mapping is: - Select maps to Map<TResult>(Func<T, TResult>) - SelectMany enables monadic composition (flatMap) for chaining optional lookups

Methods

SelectMany<TSource, TCollection, TResult>(Maybe<TSource>, Func<TSource, Maybe<TCollection>>, Func<TSource, TCollection, TResult>)

Projects each value of a Maybe to a new Maybe and flattens the result (LINQ SelectMany operation). Enables composition of multiple Maybe-returning operations in LINQ query syntax.

public static Maybe<TResult> SelectMany<TSource, TCollection, TResult>(this Maybe<TSource> source, Func<TSource, Maybe<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> resultSelector) where TSource : notnull where TCollection : notnull where TResult : notnull

Parameters

source Maybe<TSource>

The source Maybe.

collectionSelector Func<TSource, Maybe<TCollection>>

A function that returns a Maybe based on the source value.

resultSelector Func<TSource, TCollection, TResult>

A function to create the final result from the source and collection values.

Returns

Maybe<TResult>

A new Maybe with the final projected value, or None if any step produces None.

Type Parameters

TSource

The type of the source value.

TCollection

The type of the intermediate collection value.

TResult

The type of the final result value.

Remarks

This is the key method that enables LINQ query syntax with multiple 'from' clauses. It performs monadic bind (flatMap) followed by a projection.

Select<TIn, TOut>(Maybe<TIn>, Func<TIn, TOut>)

Projects the value of a Maybe using a selector function (LINQ Select operation). Maps to Map<TResult>(Func<T, TResult>).

public static Maybe<TOut> Select<TIn, TOut>(this Maybe<TIn> maybe, Func<TIn, TOut> selector) where TIn : notnull where TOut : notnull

Parameters

maybe Maybe<TIn>

The Maybe to project.

selector Func<TIn, TOut>

The projection function to apply to the value.

Returns

Maybe<TOut>

A new Maybe with the projected value, or None if the input has no value.

Type Parameters

TIn

The type of the input value.

TOut

The type of the output value.