# Fyper

> Type-safe Cypher query builder for F#. Write graph database queries using computation expressions with compile-time safety, parameterized values, and multi-backend support (Neo4j, Apache AGE).

Fyper is an F# library that lets you write Cypher queries for graph databases using F# computation expressions. It compiles F# code into parameterized Cypher strings at query construction time, preventing injection and catching errors before they reach the database.

## Key Features

- Zero boilerplate schema: plain F# records are your graph nodes and relationships
- Computation expression DSL: `cypher { for p in node<Person> do; where (p.Age > 30); select p }`
- All values parameterized by default ($p0, $p1) — no string interpolation
- Multi-backend: same query runs on Neo4j (Bolt) and Apache AGE (PostgreSQL)
- Zero dependencies in core library (only FSharp.Core)
- Cypher parser: parse Cypher strings back into typed AST
- Sub-microsecond compilation performance

## Packages

- Fyper: Core query builder and compiler (FSharp.Core only)
- Fyper.Parser: Cypher string parser (depends on Fyper)
- Fyper.Neo4j: Neo4j Bolt driver (depends on Neo4j.Driver)
- Fyper.Age: Apache AGE PostgreSQL driver (depends on Npgsql)

## CE Operations

for/where/select/selectDistinct/orderBy/orderByDesc/skip/limit/matchRel/matchPath/create/createRel/createRelWith/set/delete/detachDelete/merge/onMatch/onCreate/unwind/withClause/removeProperty/removeLabel/callProc

## Edge Direction

edge<R> (outgoing) / edgeIn<R> (incoming) / edgeUn<R> (undirected)

## Aggregation & Expression Functions

count/countDistinct/sum/avg/collect/cypherMin/cypherMax/size/caseWhen/existsRel

## Documentation

- Getting Started: https://neftedollar.com/fyper/guide/getting-started.html
- CE Operations Reference: https://neftedollar.com/fyper/reference/ce-operations.html
- API Functions: https://neftedollar.com/fyper/reference/functions.html
- Neo4j Driver: https://neftedollar.com/fyper/reference/neo4j.html
- AGE Driver: https://neftedollar.com/fyper/reference/age.html
- Architecture: https://neftedollar.com/fyper/internals/architecture.html

## Links

- GitHub: https://github.com/Neftedollar/fyper
- NuGet: https://www.nuget.org/packages/Fyper
- License: MIT