patchLib.jsonnet

{
  local id = function(x) x,
  local keySet = function(a, keyF=id)
    { [k]: true for k in std.map(keyF, a) if k != null },

  arrUnion(a, b, keyF=id)::
    local aSet = keySet(a, keyF);
    local bSet = keySet(b, keyF);
    a + std.foldl(function(acc, e) acc + (
      local key = keyF(e);
      if (key != null && std.objectHas(aSet, key)) then [] else [e]
    ), b, []),

  arrInter(a, b, keyF=id)::
    local aSet = keySet(a, keyF);
    local bSet = keySet(b, keyF);
    std.foldl(function(acc, e) acc + (
      local key = keyF(e);
      if (key != null && std.objectHas(bSet, key)) then [e] else []
    ), a, []),

  arrDiff(a, b, keyF=id)::
    local bSet = keySet(b, keyF);
    std.foldl(function(acc, e) acc + (
      local key = keyF(e);
      if (key != null && std.objectHas(bSet, key)) then [] else [e]
    ), a, []),
}