result: add Unpack (#22)

result/result.go

@@ -7,6 +7,7 @@ package result
 import (
 	"errors"
 	"fmt"
+
 	"github.com/phelmkamp/valor/optional"
 )
 
@@ -71,6 +72,12 @@ func (res Result[T]) String() string {
 	return fmt.Sprintf("{%v %v}", res.v, res.err)
 }
 
+// Unpack returns the underlying value and error.
+// This aids in assigning to variables or function arguments.
+func (res Result[T]) Unpack() (T, error) {
+	return res.v, res.err
+}
+
 // Value returns an optional.Value containing either the
 // underlying value or nothing.
 func (res Result[T]) Value() optional.Value[T] {

result/result_test.go

@@ -7,15 +7,16 @@ package result_test
 import (
 	"errors"
 	"fmt"
-	"github.com/phelmkamp/valor/optional"
-	"github.com/phelmkamp/valor/result"
-	"github.com/phelmkamp/valor/tuple/unit"
 	"io"
 	"io/fs"
 	"reflect"
 	"strconv"
 	"strings"
 	"testing"
+
+	"github.com/phelmkamp/valor/optional"
+	"github.com/phelmkamp/valor/result"
+	"github.com/phelmkamp/valor/tuple/unit"
 )
 
 // type checks
@@ -258,3 +259,12 @@ func TestResult_OfError(t *testing.T) {
 		t.Errorf("OfError() = %v, want %v", got, result.OfError[float64](nil))
 	}
 }
+
+func TestResult_Unpack(t *testing.T) {
+	if v, err := result.OfError[string](errFail).Unpack(); v != "" || err != errFail {
+		t.Errorf("Unpack() = %v %v, want %v %v", v, err, "", errFail)
+	}
+	if v, err := result.OfOk("foo").Unpack(); v != "foo" || err != nil {
+		t.Errorf("Unpack() = %v %v, want %v %v", v, err, "foo", nil)
+	}
+}

tuple/two/two_tuple.go

@@ -44,7 +44,7 @@ func TupleResultOf[T, T2 any](v T, v2 T2, err error) result.Result[Tuple[T, T2]]
 // TupleMap returns a Tuple with each value replaced by the result of each function.
 //
 // funcs.Ident can be used to leave the value unchanged.
-func TupleMap[Tp, T2p, T, T2 any](t Tuple[T, T2], f func(T) Tp, f2 func(T2) T2p) (tp Tuple[Tp, T2p]) {
+func TupleMap[T, T2, Tp, T2p any](t Tuple[T, T2], f func(T) Tp, f2 func(T2) T2p) (tp Tuple[Tp, T2p]) {
 	return TupleOf(f(t.V), f2(t.V2))
 }