DataScript – Datomic in ClojureScript | Hacker News Reader

DataScript – Datomic in ClojureScript

github.com

143 pointssgrove34 comments

Looks like a great library... It would be intriguing to try to use something like DatomicScript for the app state of an Om application.

(Edit: Read in a separate blog post that the author of DatomicScript is thinking about this already)

At the end of the day though, I still think someone (smarter than me) needs to figure out the full end-to-end solution for datomic+clojurescript, with both client and server elements.

The core question: Does it make sense to map datomic to a REST API on the server, then consume the REST on the client? Or, does it make more sense to build something more clojure-like for the client-server interface, and remove REST from the equation entirely?

A seamless datomic <-> clojurescript client/service framework is needed. I am just getting started with Om and hope to experiment with some ideas in that space. I don't think REST is the right approach. I would like to abstract everything to an AVET or sequence thereof.

https://twitter.com/richhickey/status/355394063165440000

Interesting, I get the feeling though that RH also thinks this isn't the right approach, that some more though needs to be put into the client-server interface still that goes beyond vanilla datomic.

Thing is, server-side Datomic peers work in trusted env; every peer sees everything. As you start doing something like a peer in every browser that opens your app, you need to provide it only with the part of the database. This filtering should be done two-way (what’s allowed to read, what’s allowed to push back) and is not very straightforward thing to do. It’s not even clear how this thing should be configured. Also server-side lazy loading model won’t work in JS — queries will become async. Given that, server-client communication layer can be implemented, I guess, but it won’t look like anything like vanilla Datomic peer.

i think you want the application-facing interface to remain REST (links between entities, HATEOAS), but the REST/CRUD client's transport layer wouldn't be traditional http/ajax, rather implement similar capabilities to a Datomic Peer. So a CRUD READ would query a cached Datomic index rather than touch network. Create, Update, Delete could be http/ajax or could be something else like a websocket; I believe transport to be orthogonal to the fundamental principles of REST application design.

Exciting prospect. How about DataScript for your app state + tx-listen/om-sync mirroring transactions? Might require wrapping the datascript/transact! call, and I haven't thought about reading from the cliente. Maybe as simple as lazily mirroring datascript/q calls and filling those back into the DataScript map.

Datomic is bundled with a REST server: http://docs.datomic.com/rest.html. And it includes an endpoint to subscribe to a stream of Server-Sent Events, which lets you drink from the transaction-report firehose. But there is a lot of data in that stream. I'm writing a production Pedestal app, and I could definitely use the capability to store my data on the client in the same shape as Datomic and query it with Datalog.

...now renamed to DataScript https://twitter.com/nikitonsky/status/459403600775876608

HN moderators: can you please rename the post, since the project has been renamed to DataScript: https://github.com/tonsky/datascript/commit/5beb53d7db03bd27...

Sure.

Not familiar with Datomic. Does it mean now you can reuse querying code on the server to real Datomic and on the client (in browser) to DatomicScript?

If so, it could lead to some features like latency compensation and stubs similar to Meteor's MongoDB and MiniMongo. That would be cool.

Yes, query language is almost identical.

This looks like a very interesting project although it's a bit confusing that it's named after a proprietary database.

Why is it confusing? It's a basic port of that proprietary database to JavaScript. It's not like it's something completely unrelated.

In the same way that OracleScript would be an odd choice of name for a SQL database implemented in JavaScript. Now that I say that, though, I guess there isn't really a name for what Datomic is except Datomic.

It has now been renamed to DataScript. https://twitter.com/nikitonsky/status/459403600775876608

I had no idea what this was, but after some wandering I found some background: http://en.wikipedia.org/wiki/Datalog

Datalog is apparently a subset of Prolog that's used by Datomic (a commercial database) as its query language.

Here's a quick introductory resource: http://www.learndatalogtoday.org

The SICP lectures on logic programming will provide some conceptual background if needed.

http://ocw.mit.edu/courses/electrical-engineering-and-comput...

Looks great. I could see using this for some data crunching client-side, maybe even in conjunction with something like graph.js.

Are there any examples of using this from a JavaScript-mostly app? I can see it being useful as a way to clean up existing "global variable" apps.

There isn’t—yet—but it’s a popular request and I’m now thinking it could be made accessible from JS pretty easily

Curious: why is this limited to ClojureScript? I can see this being useful in JVM Clojure in projects which do not need real or full Datomic.

he actually has a clj version in the src. https://github.com/tonsky/datomicscript/blob/master/src/dato...

It was commited accidentally. Yes, it may be translated to clojure. However, I still don’t know if I should do it, given we have in-memory db bundled with Datomic free client jar.

Isn't your work released under a less restrictive license than main Datomic?

Why even limit it to Clojure and ClojureScript? I could use this from JavaScript or PureScript as an immutable local store to replicate/merge with the backend asynchronously.

The query language is embedded in legal Clojure data structures, so it would be tricky to port to JS. That's a drawback of embedded DSL's I suppose.

Contingent on the design but not necessary. I could make something similar in PureScript.

I wouldn't use Datalog though, I got turned off on it after using Datomic at work.

Similar to Datomic, which has Java bindings and allows for query DSL be specified just as a regular String, we can do this for JS interop

From what I can see, DataScript is in-memory only. Wouldn't that be the same as downloading Datomic-free and creating an in-memory db?

How about another rename? DatomicScript was clearly a bad idea and possibly infringing. "DataScript" is just misleading. Using "_____Script" creates the appearance that is a scripting language. Perhaps "_____DB" or "_____JS" would be better.

How about "NotDatJS" (short for the "Not Datomic" JS Database)?

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