Spellllang dependent key mapping

Question

Is it possible to define mappings that only get active when a certain spelllang is set?

E.g. I want to set the following mapping, but only if I use spelllang=de.

inoremap oe ö

Answer 1

You can use a conditionnal mapping:

inoremap <expr> oe ( &spelllang == "de" ) ? "ö" : "oe"

With <expr> specified Vim knows that when it sees oe as an input it should execute the rest of the mapping as a vimscript expression and map oe to the result of this expression.

Here the expression is a conditionnal operator: if &spelllang == "de" is true then return ö otherwise return oe.

See :h :map-<expr>