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Version: v2.0

Migrate from V1 to V2

This guide helps you migrate existing UnambitiousFx.Functional code from v1 to v2.

The migration is mostly straightforward. Most pipeline APIs (Bind, Map, Ensure, Tap, Match) stay familiar.

1. Update Packages​

Update package references to v2:

dotnet add package UnambitiousFx.Functional
dotnet add package UnambitiousFx.Functional.AspNetCore
dotnet add package UnambitiousFx.Functional.xunit

If you pin versions centrally, update them in your Directory.Packages.props.

2. Move from Failures to Errors​

In v2, use the Errors namespace and error types.

Before:

using UnambitiousFx.Functional.Failures;

return Result.Failure<User>(new ValidationFailure("Email is required"));

After:

using UnambitiousFx.Functional.Errors;

return Result.Failure<User>(new ValidationError("Email is required"));

3. Rename Common Types​

Most failure types have direct error equivalents:

  • Failure -> Error
  • ValidationFailure -> ValidationError
  • NotFoundFailure -> NotFoundError
  • ConflictFailure -> ConflictError
  • UnauthorizedFailure -> UnauthorizedError
  • UnauthenticatedFailure -> UnauthenticatedError
  • ExceptionalFailure -> ExceptionalError
  • AggregateFailure -> AggregateError
  • TimeoutFailure -> TimeoutError

4. Check Result State Access​

In v2, the result state property is IsFaulted (instead of IsFailure).

Before:

if (result.IsFailure)
{
    // ...
}

After:

if (result.IsFaulted)
{
    // ...
}

IsSuccess remains available.

5. Keep Existing Pipeline Style​

Most composition code can stay as-is:

return Validate(input)
    .Bind(DoWork)
    .Ensure(x => x.IsValid, new ValidationError("Invalid state"))
    .Tap(_ => logger.LogInformation("done"));

6. ASP.NET Core Mapping​

If you use Functional.AspNetCore, verify mappings use error types (ValidationError, NotFoundError, etc.).

The default HTTP mapping behavior still follows standard semantics (400/404/409/500...).

7. xUnit Assertions​

The assertion style still starts with ShouldBe().

Update typed assertions to use error names from v2.

Quick Migration Checklist​

  • Update NuGet package versions.
  • Replace using UnambitiousFx.Functional.Failures; with using UnambitiousFx.Functional.Errors;.
  • Rename *Failure types to *Error types.
  • Replace IsFailure checks with IsFaulted.
  • Run tests and confirm HTTP mapping expectations.

See Also​