# dadhi/FastExpressionCompiler

Fast Compiler for C# Expression Trees and the lightweight LightExpression alternative. Diagnostic and code generation tools for the expressions.

Repository: https://github.com/dadhi/FastExpressionCompiler
Canonical: https://ross.abutalabs.com/products/fastexpressioncompiler
Language: C#
License: MIT
License Family: permissive
Topics: expression-tree, dryioc, delegate, il-optimizations, closure, performance, benchmark, compiler, delegates, code-generation
Last push: 2026-08-19T17:00:08+00:00

## Health v2 (maintenance only)
Score: 92/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 98, release rhythm 79, longevity 100
- inputs: {"age_days": 3701, "days_push": 14, "days_rel": 142, "gap_med": 30, "n_releases_24m": 14}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1374, forks 94 (observed 2026-08-28T04:04:32.970833+00:00)

## What it is
A .NET library that compiles C# expression trees to delegates far faster than the built-in LINQ compiler, with a lightweight LightExpression alternative and diagnostic/code-generation tools. It is widely used by DI containers, ORMs, and mappers for high-performance expression evaluation.

## Use cases
- compile expression trees faster than Expression.Compile
- speed up dependency injection container resolution
- build an ORM that evaluates expressions quickly
- reduce memory allocations when compiling lambdas
- use a lighter expression tree implementation
- diagnose and generate code from expression trees

## When to choose
- you compile many expression trees at runtime and compile time is a bottleneck
- you build a DI container, ORM, mapper, or serializer that relies on expression compilation
- you need a lightweight expression tree alternative with fast compilation

## When to avoid
- you only compile a handful of expressions once at startup
- you are not on .NET or .NET Framework 4.7.2+
- you need full parity with every System.Linq.Expressions feature

## Facets
- artifact type: library
- maturity: stable
- function: compiler, serialization, developer-tools
- domain: developer-tools, performance, programming-languages
- platform: dotnet, cross-platform
- tags: expression-trees, c-sharp, delegates, il-codegen, lightexpression, dryioc

## Member repositories
- dadhi/FastExpressionCompiler (main) score 92

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:32.970833+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:40:37.033469+00:00, confidence not recorded.
  - readme: https://github.com/dadhi/FastExpressionCompiler (fetched 2026-08-28T04:04:32.970833+00:00, sha 0670059c8eb4)
- Data as of 2026-08-30T08:39:29.467469+00:00.