Example of how lists type merge breaks

miniexample.nix

let
  pkgs = import <nixpkgs> { };
in
with pkgs.lib; with pkgs.lib.types; let

  leftType = submodule {
    options.foo = mkOption {
      type = int;
      description = "left.foo";
    };
  };

  rightType = submodule {
    options.bar = mkOption {
      type = string;
      description = "right.bar";
    };
  };

  loc = [ "dummy" ];

  leftValue = { foo = 1; };
  rightValue = { bar = 1; };
  rightValueWrong = { bar = true; };

  defs = {
    testCase1 = [
      { file = "f1"; value = [ leftValue ]; }
    ];
    testCase2 = [
      { file = "f1"; value = [ leftValue leftValue ]; }
    ];
    testCase3 = [
      { file = "f1"; value = [ leftValue leftValue ]; }
      { file = "f2"; value = [ leftValue leftValue ]; }
    ];
    testCase4 = [
      { file = "f1"; value = [ rightValue ]; }
    ];
    testCase5 = [
      { file = "f1"; value = [ leftValue ]; }
      { file = "f2"; value = [ rightValue ]; }
    ];
    testCase6 = [
      { file = "f1"; value = [ rightValueWrong ]; }
    ];
  };

  #This doesn't work because list merge breaks for inner eithers 
  callMerge = defs:
    let
      typeDef = listOf (either leftType rightType);
    in
    typeDef.merge loc defs;

  #This doesnt work because it no longer propertly checks the correctness of the records in the list 
  #Same happens if uniq is on the either 
  callMergeUniq = defs:
    let
      typeDef = uniq (listOf (either leftType rightType));
      #typeDef = listOf (uniq (either leftType rightType));
    in
    typeDef.merge loc defs;

in
{

  nonUniq = {

    testCase1 = callMerge defs.testCase1;
    testCase2 = callMerge defs.testCase2;
    testCase3 = callMerge defs.testCase3;
    #Seems like something with lists merge is funny ending up always trying to apply the first arugment of the inner either.
    #testCase4Breaks = callMerge defs.testCase4;
    #testCase5Breaks = callMerge defs.testCase5;
  };

  withUniq = {

    testCase1 = callMergeUniq defs.testCase1;
    testCase2 = callMergeUniq defs.testCase2;

    #Makes sense that it breaks since we made it uniq 
    #testCase3Breaks = callMergeUniq defs.testCase3;

    testCase4 = callMergeUniq defs.testCase4;

    #Makes sense that it breaks since we made it uniq 
    #testCase5Breaks = callMergeUniq defs.testCase5;

    testCase6 = callMergeUniq defs.testCase6;
  };
}