Read/analyze ClojureScript and conditional read sources

Description

Clojure 1.7 and ClojureScript 3308 introduced support for the Conditional Reader.

tools.namespace started out as a Clojure-only library. Support for the conditional reader was added in TNS-34, but it was hard-coded for Clojure (.clj and .cljc) files only.

Some high-level features of tools.namespace, such as code reloading via c.t.n.repl/refresh, are coupled to the Clojure(JVM) implementation, and could not easily be ported to ClojureScript. I regard that as a non-issue for now, since other tools (e.g. Figwheel) exist to do reloading in ClojureScript.

However, other features of tools.namespace, such as namespace dependency analysis, do not depend specifically on Clojure(JVM). It might be useful to apply those tools on ClojureScript source files.

The deeper problem is the multi-layered structure of tools.namespace. The Clojure/ClojureScript distinction only really matters in the "lower" layers such as c.t.n.file and c.t.n.parse, but the layered structure makes it awkward to pass options through from the "higher" layers such as c.t.n.dir and c.t.n.find.

See also comments on TNS-29.

This ticket is a place to capture work and notes about this problem.

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Stuart Sierra
November 3, 2015, 5:55 PM

.cljc support for read/parse/dependencies in 0.3.0-alpha* release

Stuart Sierra
July 26, 2015, 4:00 PM

My current thinking is:

c.t.n.dependency and c.t.n.track are platform agnostic.

c.t.n.file and c.t.n.parse can be extended to support Clojure & ClojureScript by adding an optional argument read-opts passed through to tools.reader/read.

c.t.n.find can be extended with optional arguments to select a "platform," either Clojure or ClojureScript, which will encapsulate both valid file extensions and reader options.

Reload/refresh functionality will remain Clojure(JVM) only for now: c.t.n.dir, c.t.n.reload, and c.t.n.repl.

c.t.n.move is still alpha and does not even support .cljc files. It can be handled under separate tickets or deprecated.

Work-in-progress visible on branch TNS-35-cljs-experiments currently at commit e9327295

Stuart Sierra
July 26, 2015, 12:51 AM

As far as I know, ClojureScript has used tools.reader instead of clojure.core/read for some time.

Laurent PETIT
July 25, 2015, 9:10 PM

Oh, I didn't know that. It's kind of a shame, no, since it is well known that ClojureScript is compiled via Clojure (JVM) ...

Stuart Sierra
July 25, 2015, 4:10 PM

The reason you can't just pass different options to clojure.core/read is because, on Clojure(JVM) read will always add the platform feature :clj. There is no way to call read and force it to omit the platform feature.

See the Reader Conditionals design page, "The platform feature (:clj) will always be present."

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Assignee

Stuart Sierra

Reporter

Stuart Sierra