ale/ale_linters/scala/scalac.vim

" Author: Zoltan Kalmar - https://github.com/kalmiz
" Description: Basic scala support using scalac

function! ale_linters#scala#scalac#Handle(buffer, lines) abort
    " Matches patterns line the following:
    "
    " /var/folders/5q/20rgxx3x1s34g3m14n5bq0x80000gn/T/vv6pSsy/0:26: error: expected class or object definition
    let l:pattern = '^.\+:\(\d\+\): \(\w\+\): \(.\+\)'
    let l:output = []
    let l:ln = 0

    for l:line in a:lines
        let l:ln = l:ln + 1
        let l:match = matchlist(l:line, l:pattern)

        if len(l:match) == 0
            continue
        endif

        let l:text = l:match[3]
        let l:type = l:match[2] ==# 'error' ? 'E' : 'W'
        let l:col = 0

        if l:ln + 1 < len(a:lines)
            let l:col = stridx(a:lines[l:ln + 1], '^')

            if l:col == -1
                let l:col = 0
            endif
        endif

        " vcol is Needed to indicate that the column is a character.
        call add(l:output, {
        \   'bufnr': a:buffer,
        \   'lnum': l:match[1] + 0,
        \   'vcol': 0,
        \   'col': l:col + 1,
        \   'text': l:text,
        \   'type': l:type,
        \   'nr': -1,
        \})
    endfor

    return l:output
endfunction

call ale#linter#Define('scala', {
\   'name': 'scalac',
\   'executable': 'scalac',
\   'output_stream': 'stderr',
\   'command': 'scalac -Ystop-after:parser %t',
\   'callback': 'ale_linters#scala#scalac#Handle',
\})