lib.options.mergeEqualOption

The following is the current implementation of this function.

mergeEqualOption = loc: defs:
    if defs == [] then abort "This case should never happen."
    # Return early if we only have one element
    # This also makes it work for functions, because the foldl' below would try
    # to compare the first element with itself, which is false for functions
    else if length defs == 1 then (head defs).value
    else (foldl' (first: def:
      if def.value != first.value then
        throw "The option `${showOption loc}' has conflicting definition values:${showDefs [ first def ]}\n${prioritySuggestion}"
      else
        first) (head defs) (tail defs)).value;