Time-stamp: <2024-02-11 12h13 UTC>

# Finally an APL for my flying saucer?

> Let's postpone the why and what of BQN, and address the how

Suppose that you're interested in using

=> https://mlochbaum.github.io/BQN/index.html BQN

but you're troubled by not having any. Well, if you're an Arch linux and using emacs, the following should see you through

## Building and installing

### CBQN

I found the AUR package for CBQN lacking, in that it didn't compile the shared libraries which i wanted for the LSP integration below. To that end, here's what i'm using

```
$ cat PKGBUILD
# Maintainer: Firegem <mrfiregem [at] protonail [dot] ch>
pkgname=cbqn-git
pkgver=r2743.8c18fddd
pkgrel=1
pkgdesc="A BQN implementation in C."
arch=('x86_64' 'i686' 'aarch64' 'arm')
url="https://github.com/dzaima/CBQN"
license=('Apache' 'Boost' 'GPL3' 'MIT')
depends=('glibc' 'libffi')
optdepends=('ttf-bqn386: BQN and APL compatible font')
makedepends=('git' 'clang')
provides=("${pkgname%-git}")
conflicts=("${pkgname%-git}")
source=("${pkgname%-git}::git+${url}.git")
md5sums=('SKIP')

pkgver() {
  cd "${srcdir}/${pkgname%-git}"
  printf "r%s.%s" "$(git rev-list --count HEAD)" "$(git rev-parse --short HEAD)"
}

build() {
  cd "${srcdir}/${pkgname%-git}"
  make PIE='-pie' o3n
  make PIE='-pie' shared-o3
}

package() {
  cd "${srcdir}/${pkgname%-git}"
  make PREFIX="${pkgdir}/usr/" install
}
```

the changes to build() and package() are minor, but appear to be necessary.

With that it should be possible to install a functioning BQN compiler and REPL.

#### BQN LSP

=> https://git.sr.ht/~detegr/bqnlsp

Cloning and building this should work now that the above PKGBUILD puts /usr/lib/libcbqn.so onto the file system. Not too much to say here, other than copy the resulting bqnlsp into your path somewhere

## Emacs integration

Fortunately for us, all of the hard work has already been done

```
(use-package bqn-mode
  :ensure t
  :defer
  :bind (:map bqn-mode-map
              ("M-TAB" . expand-abbrev)
              ("C-c r r" . bqn-comint-eval-dwim)
              ("C-c r b" . bqn-comint-eval-buffer))
  :hook (bqn-mode . (lambda () (eglot-ensure) (bqn-comint-buffer)))
  :config
  (require 'bqn-keymap-mode)
  (require 'bqn-glyph-mode))
```

Note that the first time this is run eglot may ask for the path of bqnlsp, simply provide it.

### Bonus round: abbrev-mode for entering symbols

At first when using BQN i found that while i could remember the names of the various glyphs in which i was interested, i could not recall where they were on the "BQN Keyboard"---a task not aided by the fact that i don't use QWERTY⁰. To that end i wrote some abbrev aliases so that i could type the names and press either space or whatever the favourite abbrev trigger was to replace the word with the glyph

```
(define-abbrev-table 'bqn-mode-abbrev-table
    '( ;; funtions
      ("abs" "│")
      ("assert" "!")
      ("ceiling" "⌈")
      ("classify" "⊐")
      ("conj" "∧")
      ("couple" "≍")
      ("deduplicate" "⍷")
      ("depth" "≡")
      ("deshape" "⥊")
      ("dgrade" "⍒")
      ("disj" "∨")
      ("divide" "÷")
      ("drop" "↓")
      ("dsort" "∧")
      ("enlist" "⋈")
      ("find" "⍷")
      ("floor" "⌊")
      ("group" "⊔")
      ("gt" ">")
      ("gte" "≥")
      ("indices" "/")
      ("join" "∾")
      ("left" "⊣")
      ("length" "≠")
      ("lshift" "«")
      ("lt" "<")
      ("lte" "≤")
      ("match" "≡")
      ("maximum" "⌈")
      ("member" "∊")
      ("minimum" "⌊")
      ("minus" "¯")
      ("modulus" "│")
      ("multiply" "×")
      ("neg" "¬")
      ("neq" "≠")
      ("nmatch" "≢")
      ("occurrence" "⊒")
      ("pair" "⋈")
      ("pick" "⊑")
      ("power" "⋆")
      ("prefix" "↑")
      ("range" "↕")
      ("recip" "÷")
      ("replicate" "/")
      ("reshape" "⥊")
      ("reverse" "⌽")
      ("right" "⊢")
      ("root" "√")
      ("rshift" "»")
      ("select" "⊏")
      ("shape" "≢")
      ("sign" "×")
      ("solo" "≍")
      ("span" "¬")
      ("sqrt" "√")
      ("suffix" "↓")
      ("take" "↑")
      ("transpose" "⍉")
      ("ugrade" "⍋")
      ("usort" "∨")
      ;; combinators
      ("atop" "∘")
      ("catch" "⎊")
      ("choose" "◶")
      ("constant" "˙")
      ("lhook" "⊸")
      ("over" "○")
      ("rhook" "⟜")
      ("self" "˜")
      ("swap" "˜")
      ("under" "⌾")
      ("valence" "⊘")
      ;; 1-modifiers
      ("cell" "˘")
      ("each" "¨")
      ("fold" "´")
      ("insert" "˝")
      ("scan" "`")
      ("table" "⌜")
      ("undo" "⁼")
      ;; 2-modifiers
      ("depth" "⚇")
      ("rank" "⎉")
      ("repeat" "⍟")
      ;; syntax
      ("define" "←")
      ("export" "⇐")
      ("change" "↩")
      ("nothing" "·")
      ("sep" "⋄")
      ;; constants
      ("pi" "π")
      ("infty" "∞")))
```

to make this not irritating i found myself also setting

```
(setq save-abbrevs 'silently)
```

and adding (abbrev-mode) to the bqn-mode hook.

Happy BQN'ing!

---

⁰ For the curious
=> https://git.sr.ht/~tslil/keyboard