Cut outdated or duplicated parts from running.md and improve explanations

1 files changed, 12 insertions, 30 deletions

diff --git a/running.md b/running.md
index 07442017..548d1c2d 100644
--- a/running.md
+++ b/running.md
@@ -2,7 +2,7 @@
 
 # How to run BQN
 
-[CBQN](https://github.com/dzaima/CBQN) is the primary offline implementation. Scripts in this repository start with `#! /usr/bin/env bqn` in order to look up the user's `bqn` executable, which is expected to be CBQN.
+CBQN is the primary offline implementation, and has [build instructions in its own repository](https://github.com/dzaima/CBQN). Here and elsewhere it's expected to be installed as `bqn`. For Windows, build in [WSL](https://en.wikipedia.org/wiki/Windows_Subsystem_for_Linux) or see WinBQN below.
 
 Third-party packages are available for Windows and a few Linux distributions. Because they run on an unknown target system, none of these packages are built with the highest-performance settings. If you need top speed (you probably don't!) you should compile CBQN for the target hardware instead.
 
@@ -15,7 +15,7 @@ Third-party packages are available for Windows and a few Linux distributions. Be
 
 For tools related to running BQN, see the [editor plugins](editors/README.md) and [fonts page](https://mlochbaum.github.io/BQN/fonts.html).
 
-All these websites run BQN (on your computer, except the CBQN ones):
+All these websites run BQN, in your browser unless marked with "server-side" (JS is native Javascript; the Wasm engine is WebAssembly compiled from CBQN).
 
 | Link | Style | Engine | Comments
 |------|-------|--------|---------
@@ -27,48 +27,30 @@ All these websites run BQN (on your computer, except the CBQN ones):
 | [ktye/zoo](https://ktye.github.io/zoo/index.html#bqn) | Session | JS | Many array languages
 | [Observable](https://observablehq.com/@lsh/bqn)  | Notebook | JS | For import in Observable
 | [BQN-80](https://dancek.github.io/bqn-80)        | One-shot | JS | Create animations
-| [week.golf](https://week.golf)                   | Challenge | CBQN | Code golf
+| [week.golf](https://week.golf)                   | Challenge | CBQN | Code golf, server-side
 
-Further details in the sections below.
+Details about CBQN as well as the Javascript and other implementations follow.
 
-### Self-hosted BQN
+## Self-hosted BQN
 
-This version of BQN is [implemented](implementation/README.md) mainly in BQN itself, but a host language supplies basic functionality and can also replace primitives for better performance. This also allows [embedding](doc/embed.md), where programs in the host language can include BQN code. It fully supports all functionality specified so far. System value support varies as it's implemented separately in each host.
+Both CBQN and JS BQN are [implemented](implementation/README.md) using components written in BQN itself: the compiler, and primitive implementations. The host language provides a bytecode VM and basic functionality for the primitives, and can replace primitives with native implementations for better performance. It also provides system values, so that which ones are supported depends on the host. This setup allows [embedding](doc/embed.md), where programs in the host language can evaluate BQN code.
 
-Support in the following languages has been implemented (details in the subsections below):
-- [C](https://github.com/dzaima/CBQN), targeting high performance. Usually fairly fast.
+Support in the following languages has been implemented:
+- [CBQN](https://github.com/dzaima/CBQN) in C, targeting high [performance](implementation/perf.md) with mostly native primitives.
 - Javascript, in this repository. Slow (compiles at ~5kB/s) but usable.
 - BQN ([bqn.bqn](bqn.bqn)), for testing without a build step.
 - [Julia](https://github.com/andreypopp/BQN.jl) embedding, with common primitives implemented natively. Slow startup.
 - [C++](https://github.com/ashermancinelli/cxbqn), planning to enable GPU use. Still slow; some cool features.
-- [Rust](https://github.com/cannadayr/rsbqn/), motivated by web use (an [Erlang](https://github.com/cannadayr/ebqn) version is abandoned as too slow). Note that CBQN [embeds in Rust](https://detegr.github.io/cbqn-rs/cbqn/) as well.
-
-#### Javascript
+- [Rust](https://github.com/cannadayr/rsbqn/), motivated by web use (an [Erlang](https://github.com/cannadayr/ebqn) version is abandoned as too slow). Note that CBQN [can run from Rust](https://detegr.github.io/cbqn-rs/cbqn/) as well.
 
 The file [docs/bqn.js](docs/bqn.js) is zero-dependency Javascript, and can be loaded from HTML or Node.js. For command line use, call the Node.js script [bqn.js](bqn.js), passing a file and `•args`, or `-e` to execute all remaining arguments directly and print the results.
 
-#### CBQN
-
-C sources are kept in the [CBQN](https://github.com/dzaima/CBQN) repository, but it also depends on bytecode from the BQN sources here. Running `make` gets a working copy right away with saved bytecode. Then to use the latest bytecode, call `$ ./BQN genRuntime …/BQN`, where `…/BQN` points to this repository, and run `make` again.
-
-CBQN is developed on Linux, and as-is will only run on Unix-like systems (including macOS). To run on Windows, [WSL](https://en.wikipedia.org/wiki/Windows_Subsystem_for_Linux) has the best support but there are also native builds based on each of Cygwin and Mingw [here](https://github.com/actalley/WinBQN).
-
-`genRuntime` can also be run with another BQN implementation (the Node.js one works but takes up to a minute), and plain `./genRuntime` uses your system's `bqn` executable. I symlink `…/CBQN/BQN` to `~/bin/bqn` so I can easily use CBQN for scripting.
-
-CBQN has native support for most primitive functionality and falls back to the self-hosted runtime to fill the gaps. The most important operations are fast, and it's almost always possible to write code that sticks to them. However, some cases, particularly those that deal with multiple axes, are much slower (although still fine for most use cases).
-
-### dzaima/BQN
+## dzaima/BQN
 
 [dzaima/BQN](https://github.com/dzaima/BQN/) is an implementation in Java created by modifying the existing dzaima/APL, and should be easy to run on desktop Linux and Android. It was historically the main implementation, but is now updated only to stay up to date with language changes. Major missing functionality is dyadic Depth (`⚇`) and set functions `⊐⊒∊⍷` with rank >1, and there are various small differences from the BQN spec, mostly to do with rank, handling of atoms, fills, and headers. It uses UTF-16 instead of UTF-32, so that characters like `𝕩` don't behave correctly.
 
-To get an executable that works like CBQN, make a script with the following contents. Scripts may use `#! /usr/bin/env dbqn` to run with dzaima/BQN specifically, but this is rare now (in this repository, only `test/dzaima` does it).
-
-    #! /bin/bash
-
-    java -jar /path/to/dzaima/BQN/BQN.jar "$@"
-
-If compiled with Native Image, `nBQN` can be used directly instead.
+The only remaining dzaima/BQN script here is `test/dzaima`, which can be used to test the self-hosted primitives but has been superseded by `test/unit`.
 
-### BQN2NGN
+## BQN2NGN
 
 [BQN2NGN](https://github.com/mlochbaum/BQN2NGN) is a prototype implementation in Javascript built to experiment with the language. It's now abandoned.