Function does not work when called as from a mapping

Question

I have a function that depends on the character under the cursor : if it's a ), then the function does nothing ; if it's not, the function adds a ).

function! Ket()
   let char = getline(".")[col('.')-1]
   if char != ')'
      execute "normal! a)\<esc>"
   endif
endfunction

If I call it from normal mode, using :call Ket(), it works fine.

But I have it remapped from insert mode, as follows :

inoremap ) <Esc>l:call Ket()<CR>a. This mapping should (from my understanding) :

• escape insert mode with <Esc>,
• go one character to the right with l (because escape to normal mode moves the cursor to the left),
• call my Ket() function,
• get back to insert mode (a)

If I am in insert mode, and my cursor is on a ) character, then I get what I expect by pressing ) : the cursor moves to the right, and I end up in insert mode.

But if my cursor is on any other character, pressing ) only escapes insert mode, as if I had pressed Esc.

Answer 1

Instead of leaving insert mode you could try to do the same without the need for a function (because in this case it's a simple case):

inoremap <expr> )  strpart(getline('.'), col('.')-1, 1) == ")" ? "\<Right>" : ")"

Decomposing:

inoremap <expr> )  

will insert the result of the mapping as instead of )

strpart(getline('.'), col('.')-1, 1) 

get the current character under cursor

== ")" ? "\<Right>" : ")"

if it's a ) insert the right key, if not, insert a ).

---

If you want to keep your function, you can do it as well like this:

function! Ket()
  if strpart(getline('.'), col('.')-1, 1) == ")" 
    return "\<Right>" 
  else
    return  ")"
  endif
endfunction

inoremap <expr> ) Ket()