feat(layer): add julia code formattor

Problem: can not format julia.
Solution: add custom neoformat configuration for julia

autoload/SpaceVim/layers/lang/julia.vim

@@ -32,7 +32,8 @@
 "   SPC l s l       send current line
 "   SPC l s s       send selection text
 " <
-"
+" To format julia code, you need to install `JuliaFormatter`, and the key
+" binding is `SPC b f`
 
 function! SpaceVim#layers#lang#julia#plugins() abort
   let plugins = []
@@ -54,6 +55,15 @@ function! SpaceVim#layers#lang#julia#config() abort
 
   " julia
   let g:default_julia_version = '0.7'
+  " format code
+  " if you want to use mirror:
+  " let $JULIA_PKG_SERVER = 'https://mirrors.tuna.tsinghua.edu.cn/julia'
+  let g:neoformat_enabled_julia = ['juliafmt']
+  let g:neoformat_julia_juliafmt = {
+        \ 'exe': 'julia',
+        \ 'args': ['-e', '"using JuliaFormatter; print(format_text(read(stdin, String)))"'],
+        \ 'stdin': 1,
+        \ }
 endfunction
 
 function! s:language_specified_mappings() abort

doc/SpaceVim.txt

@@ -2982,7 +2982,8 @@ This layer also provides REPL support for julia, the key bindings are:
   SPC l s l       send current line
   SPC l s s       send selection text
 <
-
+To format julia code, you need to install `JuliaFormatter`, and the key
+binding is `SPC b f`
 
 ==============================================================================
 LANG#KOTLIN                                      *SpaceVim-layers-lang-kotlin*