#2132 - Replace all uses of foo_callback with foo

ale_linters/ruby/ruby.vim

@@ -5,7 +5,7 @@ call ale#Set('ruby_ruby_executable', 'ruby')
 
 call ale#linter#Define('ruby', {
 \   'name': 'ruby',
-\   'executable_callback': ale#VarFunc('ruby_ruby_executable'),
+\   'executable': {b -> ale#Var(b, 'ruby_ruby_executable')},
 \   'command': '%e -w -c -T1 %t',
 \   'output_stream': 'stderr',
 \   'callback': 'ale#handlers#ruby#HandleSyntaxErrors',