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Merge pull request #756 from polyadic/upcast
Implement `UpCast<T>.From(...)`
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,60 @@ | ||
| using System.Collections.Immutable; | ||
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| namespace Funcky.Test; | ||
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| public sealed class UpCastTest | ||
| { | ||
| [Fact] | ||
| public void UpCastsReferenceTypeToObject() | ||
| { | ||
| const string arbitraryStringValue = "string"; | ||
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| Option<object> option = UpCast<object>.From(Option.Return(arbitraryStringValue)); | ||
| FunctionalAssert.Some(arbitraryStringValue, option); | ||
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| Either<Unit, object> either = UpCast<object>.From(Either<Unit>.Return(arbitraryStringValue)); | ||
| FunctionalAssert.Right(arbitraryStringValue, either); | ||
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| Result<object> result = UpCast<object>.From(Result.Return(arbitraryStringValue)); | ||
| FunctionalAssert.Ok(arbitraryStringValue, result); | ||
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| Lazy<object> lazy = UpCast<object>.From(Lazy.Return(arbitraryStringValue)); | ||
| Assert.Equal(arbitraryStringValue, lazy.Value); | ||
| } | ||
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| [Fact] | ||
| public void UpCastsValueTypeToObject() | ||
| { | ||
| const int arbitraryIntegerValue = 10; | ||
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| Option<object> option = UpCast<object>.From(Option.Return(arbitraryIntegerValue)); | ||
| FunctionalAssert.Some(arbitraryIntegerValue, option); | ||
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| Either<Unit, object> either = UpCast<object>.From(Either<Unit>.Return(arbitraryIntegerValue)); | ||
| FunctionalAssert.Right(arbitraryIntegerValue, either); | ||
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| Result<object> result = UpCast<object>.From(Result.Return(arbitraryIntegerValue)); | ||
| FunctionalAssert.Ok(arbitraryIntegerValue, result); | ||
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| Lazy<object> lazy = UpCast<object>.From(Lazy.Return(arbitraryIntegerValue)); | ||
| Assert.Equal(arbitraryIntegerValue, lazy.Value); | ||
| } | ||
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| [Fact] | ||
| public void UpCastsToInterface() | ||
| { | ||
| var arbitraryImplementationValue = ImmutableArray<string>.Empty; | ||
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| Option<IEnumerable<string>> option = UpCast<IEnumerable<string>>.From(Option.Return(arbitraryImplementationValue)); | ||
| FunctionalAssert.Some(arbitraryImplementationValue, option); | ||
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| Either<Unit, IEnumerable<string>> either = UpCast<IEnumerable<string>>.From(Either<Unit>.Return(arbitraryImplementationValue)); | ||
| FunctionalAssert.Right(arbitraryImplementationValue, either); | ||
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| Result<IEnumerable<string>> result = UpCast<IEnumerable<string>>.From(Result.Return(arbitraryImplementationValue)); | ||
| FunctionalAssert.Ok(arbitraryImplementationValue, result); | ||
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| Lazy<IEnumerable<string>> lazy = UpCast<IEnumerable<string>>.From(Lazy.Return(arbitraryImplementationValue)); | ||
| Assert.Equal(arbitraryImplementationValue, lazy.Value); | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,54 @@ | ||
| using System.Diagnostics.CodeAnalysis; | ||
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| namespace Funcky; | ||
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| /// <summary>Functions to upcast monad values.</summary> | ||
| public static class UpCast<TResult> | ||
| where TResult : notnull | ||
| { | ||
| /// <summary>Upcasts an <see cref="Option{TItem}"/>'s item to <typeparamref name="TResult"/>.</summary> | ||
| /// <example> | ||
| /// Upcasting an option's item from <see cref="string"/> to <see cref="object"/>: | ||
| /// <code><![CDATA[ | ||
| /// Option<object> result = UpCast<object>.From(Option.Return("hello world")); | ||
| /// ]]></code></example> | ||
| public static Option<TResult> From<TItem>(Option<TItem> option) | ||
| where TItem : TResult | ||
| => option.Select(From); | ||
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| /// <summary>Upcasts the right side of an <see cref="Either{TLeft,TRight}"/> to <typeparamref name="TResult"/>.</summary> | ||
| /// <example> | ||
| /// Upcasting an either's right value from <see cref="string"/> to <see cref="object"/>: | ||
| /// <code><![CDATA[ | ||
| /// Either<Error, object> result = UpCast<object>.From(Either<Error>.Return("hello world")); | ||
| /// ]]></code></example> | ||
| public static Either<TLeft, TResult> From<TLeft, TRight>(Either<TLeft, TRight> either) | ||
| where TLeft : notnull | ||
| where TRight : TResult | ||
| => either.Select(From); | ||
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| /// <summary>Upcasts the success result of a <see cref="Result{TValidResult}"/> to <typeparamref name="TResult"/>.</summary> | ||
| /// <example> | ||
| /// Upcasting a result's success value from <see cref="string"/> to <see cref="object"/>: | ||
| /// <code><![CDATA[ | ||
| /// Result<object> result = UpCast<object>.From(Result.Return("hello world")); | ||
| /// ]]></code></example> | ||
| public static Result<TResult> From<TValidResult>(Result<TValidResult> result) | ||
| where TValidResult : TResult | ||
| => result.Select(From); | ||
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| /// <summary>Upcasts the value of a <see cref="Lazy{TValidResult}"/> to <typeparamref name="TResult"/>.</summary> | ||
| /// <example> | ||
| /// Upcasting a lazy's value from <see cref="string"/> to <see cref="object"/>: | ||
| /// <code><![CDATA[ | ||
| /// Lazy<object> result = UpCast<object>.From(Lazy.Return("hello world")); | ||
| /// ]]></code></example> | ||
| [UnconditionalSuppressMessage("Trimming", "IL2091", Justification = "Public parameterless constructor is only used when a Lazy is created without providing a value or func.")] | ||
| public static Lazy<TResult> From<T>(Lazy<T> lazy) | ||
| where T : TResult | ||
| => lazy.Select(From); | ||
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| private static TResult From<TValue>(TValue value) | ||
| where TValue : TResult | ||
| => value; | ||
| } |