Troubleshooting Types

Mon, 01 Jan 0001 00:00:00 +0000

Troubleshooting Types

This page shows the compiler errors that usually mean you crossed a wrapper boundary in the wrong place.

Most FsFlow type errors are not exotic. The compiler usually sees one wrapper shape and you intended another.

Error: A Unique Overload For Method `Bind` Could Not Be Determined

This usually happens when the compiler cannot tell which wrapper shape a let! value should use.

Example:

let nested : Async<Async<Result<int, string>>> =
    async {
        return async { return Ok 42 }
    }

let workflow : Flow<unit, string, int> =
    flow {
        let! next = nested
        let! value = next
        return value
    }

The second let! is ambiguous.

Benchmarks

Mon, 01 Jan 0001 00:00:00 +0000

Benchmarks

This page shows the performance tradeoffs of using FsFlow compared to manual result/async/task composition.

The benchmarks are measured with BenchmarkDotNet and represent the abstraction cost for typical application code.

Summary

abstraction cost is negligible for effectful code
cold execution for task-oriented computations adds small allocation overhead compared to hot ValueTask
performance is competitive with manual Async<Result<'T, 'E>> composition

Setup

All measurements were taken on:

.NET 8.0
Ubuntu 22.04
AMD Ryzen 9 5950X

Abstraction Cost

Measures a 20-step bind sequence where each step is pure. This is the “worst case” for FsFlow because the abstraction cost is not hidden by actual I/O or async work.

Patterns on FsFlow

Troubleshooting Types

Troubleshooting Types

Error: A Unique Overload For Method Bind Could Not Be Determined

Benchmarks

Benchmarks

Summary

Setup

Abstraction Cost

Error: A Unique Overload For Method `Bind` Could Not Be Determined