Deterministic hash code generation for the Pure ecosystem — stable, byte-enumerable hashes over immutable primitive types.

Pure.HashCodes provides a single entry point — DeterminedHash — that produces a stable, ordered sequence of bytes for any value implementing a Pure.Primitives.Abstractions interface. Unlike object.GetHashCode(), the output is deterministic across processes and runtimes and can be combined from multiple fields into a single compound hash.

GetHashCode() and ToString() are intentionally unsupported on DeterminedHash and throw NotSupportedException — callers must consume the byte sequence directly.

DeterminedHash is a sealed record implementing IDeterminedHash : IEnumerable<byte>.

• Deterministic — identical inputs always produce identical byte sequences, regardless of runtime or process lifetime.
• Abstraction-driven — works exclusively with Pure.Primitives.Abstractions interfaces, not concrete types.
• Composable — multiple DeterminedHash values can be aggregated into a single compound hash via IEnumerable<IDeterminedHash>.
• AOT-compatible — the library is fully compatible with Native AOT compilation.

• Pure.HashCodes.Abstractions — defines IDeterminedHash : IEnumerable<byte>, the core hash abstraction
• Pure.Primitives.Abstractions — read-only interfaces for primitive types (IBool, IChar, IDate, ITime, IDateTime, IDayOfWeek, INumber<T>, IGuid, IString)

• .NET 7
• .NET 8
• .NET 9
• .NET 10

dotnet add package Pure.HashCodes

Hash a single primitive:

using Pure.HashCodes;
using Pure.Primitives.Number;

INumber<int> id = new Int(42);
IEnumerable<byte> hashBytes = new DeterminedHash(id);

Combine multiple fields into a compound hash:

using Pure.HashCodes;
using Pure.HashCodes.Abstractions;

IDeterminedHash nameHash = new DeterminedHash(name);
IDeterminedHash dateHash = new DeterminedHash(birthDate);

IEnumerable<byte> compound = new DeterminedHash(new[] { nameHash, dateHash });