From 6857ae6b35796c3dac1263f1c91260ff5164755d Mon Sep 17 00:00:00 2001
From: Valentin Waeselynck <vwaeselynck@ap2s.fr>
Date: Fri, 12 Oct 2018 14:26:22 +0200
Subject: [PATCH] partial README

---
 README.md   | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 project.clj |  2 +-
 2 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index e6d202e..2414ae9 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,77 @@
 # d2q
 
-A Clojure library which provides a generic, expressive, efficient way of implementing query servers for demand-driven languages such as GraphQL.
+A simple, efficient, generally applicable engine for implementing graph-pulling API servers in Clojure. 
 
-**Project status:** less than alpha, open-sourced to allow for development outside of the company. Do not use yet, as major breaking changes will occur soon. 
+**Project status: alpha, subject to change.** The core algorithm has been running in production for several months now,
+ but I'm still working on improvemnts on the API (names etc.).
+
+
+## Introduction
+
+**d2q** (_Demand-Driven Querying_) addresses some perceived limitations of various graph-pulling server-side libraries
+ (GraphQL libraries, Datomic Pull, Pathom, Walkable etc.)
+ in the Clojure ecosystem, especially regarding their performance characteristics (N+1 problem),
+ genericity, programmability or simplicity.
+
+It does so by providing by providing an execution engine for a **general, data-oriented query language,**
+ which allows for registering data-fetching logic in a way that is declarative,
+ expressive, and friendly to performance.
+
+## Features
+
+An **expressive, programmable query language:**
+  
+* **Similar expressiveness** to GraphQL, Datomic Pull, Om Next (aims to become strictly more expressive in future evolutions,
+ so as to become a compilation target for these languages), supporting in particular **parameterized Fields** (`:d2q-fcall-arg`)
+ and **aliases** (`:d2q-fcall-key`).
+* **Data-oriented,** based on maps to enable **custom application-specific annotations,**
+ while providing a keyword/vector shorthand syntax for brevity.
+* **Simple:** the information model for queries is minimalist, and not coupled to types,
+ data encoding, templating, or writes - you can take care of those aspects separately.
+* **Advanced error management:** errors are enriched with relevant query execution data
+ (equivalent to stack traces and code location) and don't prevent the server from returning
+ a partial result.
+
+A **functional, performance-friendly backend API:**
+
+* **Simple:** schema declaration is independent from data fetching
+* **Batching by default:** for data fetching / computation, d2q Resolvers
+ process entities and fields in batches (instead of computing one field of one entity,
+ e.g 'the first name of user 42', d2q Resolvers compute several fields for several entities, 
+ e.g 'the first names, last names and emails of users 42, 56, and 37').
+ This **eliminates the N+1 query problem,** and makes it more straightforward to compute 
+ derived fields or incorporate nontrivial security policies,
+ without being too demanding to the application programmer (fetching a single value from the database
+ is very easy, but fetching a table is usually not much harder).
+* **Event-driven by default,** based on [Manifold](https://github.com/ztellman/manifold),
+ allowing for non-blocking IO and controlled resource utilization.
+* a **Functional, data-oriented API:** d2q Resolvers receive and output plain Clojure data;
+ thanks to the batching behaviour, no [side-effectful workarounds](https://github.com/facebook/dataloader)
+ are required to achieve the performance you deserve.
+* If you need even more performance or control, **subquery previews**, **whole-selection processing**
+ and **early results substitution** make room for even more optimization.
+
+
+## Planned features
+
+* **conditional queries:** execute some subqueries 
+* **(mutually) recursive queries:** continue execution by jumping to another point in the query tree (now a graph).
+* various **backend auxiliary libraries**, e.g `d2q.backend.jdbc`, `d2q.backend.datomic-peer`, etc.
+* **Om Next -> d2q** adapter
+* **GraphQL -> d2q** adapter
 
 ## Usage
 
-TBD
+* [Tutorial in examples](./test/d2q/test/example/persons.clj)
+FIXME d2q-examples
+
+## Comparison to other libraries
+
+FIXME
+
+## Rationale
+
+FIXME
 
 ## License
 
diff --git a/project.clj b/project.clj
index 7cc4f04..266ff80 100644
--- a/project.clj
+++ b/project.clj
@@ -1,5 +1,5 @@
 (defproject vvvvalvalval/d2q "0.0.1-SNAPSHOT"
-  :description "An expressive toolkit for building efficient GraphQL-like query servers"
+  :description "An expressive, efficient, generally applicable engine for implementing graph-pulling API servers in Clojure."
   :url "https://github.com/vvvvalvalval/d2q"
   :license {:name "MIT License"
             :url "https://opensource.org/licenses/MIT"}