How can I convert vim8 function mapping to vim9?

Question

I have a function in vim8 as:

function! BSkipQuickFix(command)
  let start_buffer = bufnr('%')
  execute a:command
  while &buftype ==# 'quickfix' && bufnr('%') != start_buffer
    execute a:command
  endwhile
endfunction

nnoremap <F12> :call BSkipQuickFix("bn")<CR>
nnoremap <S-F12> :call BSkipQuickFix("bp")<CR>

which I have converted to vim9 as:

def BSkipQuickFix(command: string): string
  let start_buffer = bufnr('%')
  execute a:command
  while &buftype ==# 'quickfix' && bufnr('%') != start_buffer
    execute a:command
  endwhile
enddef

nnoremap <F12> : BSkipQuickFix("bn")<CR>
nnoremap <S-F12> : BSkipQuickFix("bp")<CR>

Now, I am getting E117: Unknown function: BSkipQuickFix. Any help please?

Answer 1

I would go with :h vim9-differences before converting legacy to vim9 script.

In your def function:

0. remove last : string in def as function returns nothing
1. let should be replaced with var
2. a:command should be replaced with command
3. nnoremap should use <scriptcmd>BSkipQuickFix("bn")<CR> without :