Unverified Commit 9d3e6499 authored by Johannes Kirschbauer's avatar Johannes Kirschbauer Committed by GitHub
Browse files

lib.types: init mergeTypes (#364620)

parents 04757606 3c911b2a

lib/tests/misc.nix

+41 −0
Original line number Diff line number Diff line
@@ -2612,4 +2612,45 @@ runTests { 
    };

    expected = "c";

  };



  testMergeTypesSimple =

    let

      mergedType = types.mergeTypes types.str types.str;

    in

  {

    expr = mergedType.name;

    expected = "str";

  };



  testMergeTypesFail =

    let

      mergedType = types.mergeTypes types.str types.int;

    in

  {

    expr = types.isType "merge-error" mergedType;

    expected = true;

  };



  testMergeTypesEnum =

    let

      enumAB = lib.types.enum ["A" "B"];

      enumXY = lib.types.enum ["X" "Y"];

      merged = lib.types.mergeTypes enumAB enumXY; # -> enum [ "A" "B" "X" "Y" ]

    in

  {

    expr = {

      checkA = merged.check "A";

      checkB = merged.check "B";

      checkX = merged.check "X";

      checkY = merged.check "Y";

      checkC = merged.check "C";

    };

    expected = {

      checkA = true;

      checkB = true;

      checkX = true;

      checkY = true;

      checkC = false;

    };

  };

}

lib/types.nix

+47 −0
Original line number Diff line number Diff line
@@ -1125,6 +1125,53 @@ rec { 
    addCheck = elemType: check: elemType // { check = x: elemType.check x && check x; };



  };



  /**

    Merges two option types together.



    :::{.note}

    Uses the type merge function of the first type, to merge it with the second type.



    Usually types can only be merged if they are of the same type

    :::



    # Inputs



    : `a` (option type): The first option type.

    : `b` (option type): The second option type.



    # Returns



    - The merged option type.

    - `{ _type = "merge-error"; error = "Cannot merge types"; }` if the types can't be merged.



    # Examples

    :::{.example}

    ## `lib.types.mergeTypes` usage example

    ```nix

    let

      enumAB = lib.types.enum ["A" "B"];

      enumXY = lib.types.enum ["X" "Y"];

      # This operation could be notated as: [ A ] | [ B ] -> [ A B ]

      merged = lib.types.mergeTypes enumAB enumXY; # -> enum [ "A" "B" "X" "Y" ]

    in

      assert merged.check "A"; # true

      assert merged.check "B"; # true

      assert merged.check "X"; # true

      assert merged.check "Y"; # true

      merged.check "C" # false

    ```

    :::

  */

  mergeTypes = a: b:

    assert isOptionType a && isOptionType b;

    let

      merged = a.typeMerge b.functor;

    in

    if merged == null then

      setType "merge-error" { error = "Cannot merge types"; }

    else

      merged;

};



in outer_types // outer_types.types