Support gleamlsp language server for gleam (#4696)

ale_linters/gleam/gleamlsp.vim

@@ -0,0 +1,18 @@
+" Author: Jonathan Palardt https://github.com/jpalardy
+" Description: Support for Gleam Language Server
+
+call ale#Set('gleam_gleamlsp_executable', 'gleam')
+
+function! ale_linters#gleam#gleamlsp#GetProjectRoot(buffer) abort
+    let l:gleam_toml = ale#path#FindNearestFile(a:buffer, 'gleam.toml')
+
+    return !empty(l:gleam_toml) ? fnamemodify(l:gleam_toml, ':p:h') : ''
+endfunction
+
+call ale#linter#Define('gleam', {
+\   'name': 'gleamlsp',
+\   'lsp': 'stdio',
+\   'executable': {buffer -> ale#Var(buffer, 'gleam_gleamlsp_executable')},
+\   'command': '%e lsp',
+\   'project_root': function('ale_linters#gleam#gleamlsp#GetProjectRoot'),
+\})