diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..4c49bd7
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.env
diff --git a/converters.go b/converters.go
new file mode 100644
index 0000000..aaec516
--- /dev/null
+++ b/converters.go
@@ -0,0 +1,89 @@
+package envvars
+
+import (
+	"errors"
+	"strconv"
+	"unicode/utf8"
+)
+
+func ConvertString(s string) (string, error) {
+	return s, nil
+}
+
+func ConvertRune(s string) (rune, error) {
+	rn, _ := utf8.DecodeRuneInString(s)
+	if rn == utf8.RuneError {
+		return 0, errors.New("rune decoding failed")
+	}
+	return rn, nil
+}
+
+func ConvertInt64(s string) (int64, error) {
+	return strconv.ParseInt(s, 10, 64)
+}
+
+func ConvertInt32(s string) (int32, error) {
+	v, err := strconv.ParseInt(s, 10, 32)
+	return int32(v), err
+}
+
+func ConvertInt16(s string) (int16, error) {
+	v, err := strconv.ParseInt(s, 10, 16)
+	return int16(v), err
+}
+
+func ConvertInt8(s string) (int8, error) {
+	v, err := strconv.ParseInt(s, 10, 8)
+	return int8(v), err
+}
+
+func ConvertInt(s string) (int, error) {
+	v, err := strconv.ParseInt(s, 10, 64)
+	return int(v), err
+}
+
+func ConvertUint64(s string) (uint64, error) {
+	return strconv.ParseUint(s, 10, 64)
+}
+
+func ConvertUint32(s string) (uint32, error) {
+	v, err := strconv.ParseUint(s, 10, 32)
+	return uint32(v), err
+}
+
+func ConvertUint16(s string) (uint16, error) {
+	v, err := strconv.ParseUint(s, 10, 16)
+	return uint16(v), err
+}
+
+func ConvertUint8(s string) (uint8, error) {
+	v, err := strconv.ParseUint(s, 10, 8)
+	return uint8(v), err
+}
+
+func ConvertUint(s string) (uint, error) {
+	v, err := strconv.ParseUint(s, 10, 64)
+	return uint(v), err
+}
+
+func ConvertFloat64(s string) (float64, error) {
+	return strconv.ParseFloat(s, 64)
+}
+
+func ConvertFloat32(s string) (float32, error) {
+	v, err := strconv.ParseFloat(s, 32)
+	return float32(v), err
+}
+
+func ConvertComplex128(s string) (complex128, error) {
+	return strconv.ParseComplex(s, 128)
+}
+
+func ConvertComplex64(s string) (complex64, error) {
+	v, err := strconv.ParseComplex(s, 64)
+	return complex64(v), err
+}
+
+func ConvertBool(s string) (bool, error) {
+	return strconv.ParseBool(s)
+}
diff --git a/object.go b/object.go
new file mode 100644
index 0000000..478476c
--- /dev/null
+++ b/object.go
@@ -0,0 +1,34 @@
+package envvars
+
+import (
+	"os"
+	"strings"
+)
+
+func Object[T any](key string, defaultValue T, converter func(string) (T, error)) T {
+	if v, ok := os.LookupEnv(key); ok {
+		if v2, err := converter(v); err == nil {
+			return v2
+		}
+	}
+	return defaultValue
+}
+
+func ObjectSlice[T any](key, sep string, defaultValue []T, converter func(string) (T, error)) []T {
+	return Object(key, defaultValue, func(s string) ([]T, error) {
+		if s == "" {
+			return []T{}, nil
+		}
+
+		splits := strings.Split(s, sep)
+		values := make([]T, 0, len(splits))
+		for _, s := range splits {
+			v, err := converter(s)
+			if err != nil {
+				return values, err
+			}
+			values = append(values, v)
+		}
+		return values, nil
+	})
+}
diff --git a/slices.go b/slices.go
index eabe60f..9204814 100644
--- a/slices.go
+++ b/slices.go
@@ -1,172 +1,79 @@
 package envvars
 
-import (
-	"os"
-	"strconv"
-	"strings"
-)
+import "time"
 
-func StringSlice(key, sep string) []string {
-	if v, ok := os.LookupEnv(key); ok && strings.TrimSpace(v) != "" {
-		return strings.Split(v, sep)
-	}
-	return []string{}
+func StringSlice(key, sep string, defaultValue []string) []string {
+	return ObjectSlice(key, sep, defaultValue, ConvertString)
 }
 
-func ByteSlice(key, sep string) []byte {
-	return []byte(String(key, ""))
+func ByteSlice(key, sep string, defaultValue []byte) []byte {
+	return Uint8Slice(key, sep, defaultValue)
 }
 
-func RuneSlice(key, sep string) []rune {
-	return []rune(String(key, ""))
+func RuneSlice(key, sep string, defaultValue []rune) []rune {
+	return ObjectSlice(key, sep, defaultValue, ConvertRune)
 }
 
-func IntSlice(key, sep string) []int {
-	res := make([]int, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseInt(s, 10, 64); err == nil {
-			res = append(res, int(v))
-		}
-	}
-	return res
+func IntSlice(key, sep string, defaultValue []int) []int {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt)
 }
 
-func Int8Slice(key, sep string) []int8 {
-	res := make([]int8, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseInt(s, 10, 64); err == nil {
-			res = append(res, int8(v))
-		}
-	}
-	return res
+func Int8Slice(key, sep string, defaultValue []int8) []int8 {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt8)
 }
 
-func Int16Slice(key, sep string) []int16 {
-	res := make([]int16, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseInt(s, 10, 64); err == nil {
-			res = append(res, int16(v))
-		}
-	}
-	return res
+func Int16Slice(key, sep string, defaultValue []int16) []int16 {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt16)
 }
 
-func Int32Slice(key, sep string) []int32 {
-	res := make([]int32, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseInt(s, 10, 64); err == nil {
-			res = append(res, int32(v))
-		}
-	}
-	return res
+func Int32Slice(key, sep string, defaultValue []int32) []int32 {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt32)
 }
 
-func Int64Slice(key, sep string) []int64 {
-	res := make([]int64, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseInt(s, 10, 64); err == nil {
-			res = append(res, v)
-		}
-	}
-	return res
+func Int64Slice(key, sep string, defaultValue []int64) []int64 {
+	return ObjectSlice(key, sep, defaultValue, ConvertInt64)
 }
 
-func Uint8Slice(key, sep string) []uint8 {
-	res := make([]uint8, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseUint(s, 10, 64); err == nil {
-			res = append(res, uint8(v))
-		}
-	}
-	return res
+func Uint8Slice(key, sep string, defaultValue []uint8) []uint8 {
+	return ObjectSlice(key, sep, defaultValue, ConvertUint8)
 }
 
-func Uint16Slice(key, sep string) []uint16 {
-	res := make([]uint16, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseUint(s, 10, 64); err == nil {
-			res = append(res, uint16(v))
-		}
-	}
-	return res
+func Uint16Slice(key, sep string, defaultValue []uint16) []uint16 {
+	return ObjectSlice(key, sep, defaultValue, ConvertUint16)
 }
 
-func Uint32Slice(key, sep string) []uint32 {
-	res := make([]uint32, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseUint(s, 10, 64); err == nil {
-			res = append(res, uint32(v))
-		}
-	}
-	return res
+func Uint32Slice(key, sep string, defaultValue []uint32) []uint32 {
+	return ObjectSlice(key, sep, defaultValue, ConvertUint32)
 }
 
-func Uint64Slice(key, sep string) []uint64 {
-	res := make([]uint64, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseUint(s, 10, 64); err == nil {
-			res = append(res, v)
-		}
-	}
-	return res
+func Uint64Slice(key, sep string, defaultValue []uint64) []uint64 {
+	return ObjectSlice(key, sep, defaultValue, ConvertUint64)
 }
 
-func Float32Slice(key, sep string) []float32 {
-	res := make([]float32, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseFloat(s, 64); err == nil {
-			res = append(res, float32(v))
-		}
-	}
-	return res
+func Float32Slice(key, sep string, defaultValue []float32) []float32 {
+	return ObjectSlice(key, sep, defaultValue, ConvertFloat32)
 }
 
-func Float64Slice(key, sep string) []float64 {
-	res := make([]float64, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseFloat(s, 64); err == nil {
-			res = append(res, v)
-		}
-	}
-	return res
+func Float64Slice(key, sep string, defaultValue []float64) []float64 {
+	return ObjectSlice(key, sep, defaultValue, ConvertFloat64)
 }
 
-func Complex64Slice(key, sep string) []complex64 {
-	res := make([]complex64, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseComplex(s, 64); err == nil {
-			res = append(res, complex64(v))
-		}
-	}
-	return res
+func Complex64Slice(key, sep string, defaultValue []complex64) []complex64 {
+	return ObjectSlice(key, sep, defaultValue, ConvertComplex64)
 }
 
-func Complex128Slice(key, sep string) []complex128 {
-	res := make([]complex128, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseComplex(s, 64); err == nil {
-			res = append(res, v)
-		}
-	}
-	return res
+func Complex128Slice(key, sep string, defaultValue []complex128) []complex128 {
+	return ObjectSlice(key, sep, defaultValue, ConvertComplex128)
 }
 
-func BoolSlice(key, sep string) []bool {
-	res := make([]bool, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := strconv.ParseBool(s); err == nil {
-			res = append(res, v)
-		}
-	}
-	return res
+func BoolSlice(key, sep string, defaultValue []bool) []bool {
+	return ObjectSlice(key, sep, defaultValue, ConvertBool)
 }
 
-func ObjectSlice[T any](key, sep string, converter func(string) (T, error)) []T {
-	res := make([]T, 0)
-	for _, s := range StringSlice(key, sep) {
-		if v, err := converter(s); err == nil {
-			res = append(res, v)
-		}
-	}
-	return res
+func TimeSlice(key, sep string, defaultValue []time.Time, layout string) []time.Time {
+	return ObjectSlice(key, sep, defaultValue, func(s string) (time.Time, error) { return time.Parse(layout, s) })
+}
+
+func DurationSlice(key, sep string, defaultValue []time.Duration) []time.Duration {
+	return ObjectSlice(key, sep, defaultValue, time.ParseDuration)
 }
diff --git a/vars.go b/vars.go
index 74062da..591dbd3 100644
--- a/vars.go
+++ b/vars.go
@@ -1,15 +1,9 @@
 package envvars
 
-import (
-	"os"
-	"strconv"
-)
+import "time"
 
 func String(key, defaultValue string) string {
-	if v, ok := os.LookupEnv(key); ok {
-		return v
-	}
-	return defaultValue
+	return Object(key, defaultValue, ConvertString)
 }
 
 func Byte(key string, defaultValue byte) byte {
@@ -17,143 +11,73 @@ func Byte(key string, defaultValue byte) byte {
 }
 
 func Rune(key string, defaultValue rune) rune {
-	for _, rn := range String(key, string(defaultValue)) {
-		return rn
-	}
-	return defaultValue
-}
-
-func Int(key string, defaultValue int) int {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseInt(v, 10, 64); err == nil {
-			return int(v2)
-		}
-	}
-	return defaultValue
-}
-
-func Int8(key string, defaultValue int8) int8 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseInt(v, 10, 64); err == nil {
-			return int8(v2)
-		}
-	}
-	return defaultValue
-}
-
-func Int16(key string, defaultValue int16) int16 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseInt(v, 10, 64); err == nil {
-			return int16(v2)
-		}
-	}
-	return defaultValue
-}
-
-func Int32(key string, defaultValue int32) int32 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseInt(v, 10, 64); err == nil {
-			return int32(v2)
-		}
-	}
-	return defaultValue
+	return Object(key, defaultValue, ConvertRune)
 }
 
 func Int64(key string, defaultValue int64) int64 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseInt(v, 10, 64); err == nil {
-			return v2
-		}
-	}
-	return defaultValue
+	return Object(key, defaultValue, ConvertInt64)
 }
 
-func Uint8(key string, defaultValue uint8) uint8 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseUint(v, 10, 64); err == nil {
-			return uint8(v2)
-		}
-	}
-	return defaultValue
+func Int32(key string, defaultValue int32) int32 {
+	return Object(key, defaultValue, ConvertInt32)
 }
 
-func Uint16(key string, defaultValue uint16) uint16 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseUint(v, 10, 64); err == nil {
-			return uint16(v2)
-		}
-	}
-	return defaultValue
+func Int16(key string, defaultValue int16) int16 {
+	return Object(key, defaultValue, ConvertInt16)
 }
 
-func Uint32(key string, defaultValue uint32) uint32 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseUint(v, 10, 64); err == nil {
-			return uint32(v2)
-		}
-	}
-	return defaultValue
+func Int8(key string, defaultValue int8) int8 {
+	return Object(key, defaultValue, ConvertInt8)
+}
+
+func Int(key string, defaultValue int) int {
+	return Object(key, defaultValue, ConvertInt)
 }
 
 func Uint64(key string, defaultValue uint64) uint64 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseUint(v, 10, 64); err == nil {
-			return v2
-		}
-	}
-	return defaultValue
+	return Object(key, defaultValue, ConvertUint64)
 }
 
-func Float32(key string, defaultValue float32) float32 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseFloat(v, 64); err == nil {
-			return float32(v2)
-		}
-	}
-	return defaultValue
+func Uint32(key string, defaultValue uint32) uint32 {
+	return Object(key, defaultValue, ConvertUint32)
+}
+
+func Uint16(key string, defaultValue uint16) uint16 {
+	return Object(key, defaultValue, ConvertUint16)
+}
+
+func Uint8(key string, defaultValue uint8) uint8 {
+	return Object(key, defaultValue, ConvertUint8)
+}
+
+func Uint(key string, defaultValue uint) uint {
+	return Object(key, defaultValue, ConvertUint)
 }
 
 func Float64(key string, defaultValue float64) float64 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseFloat(v, 64); err == nil {
-			return v2
-		}
-	}
-	return defaultValue
+	return Object(key, defaultValue, ConvertFloat64)
 }
 
-func Complex64(key string, defaultValue complex64) complex64 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseComplex(v, 64); err == nil {
-			return complex64(v2)
-		}
-	}
-	return defaultValue
+func Float32(key string, defaultValue float32) float32 {
+	return Object(key, defaultValue, ConvertFloat32)
 }
 
 func Complex128(key string, defaultValue complex128) complex128 {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseComplex(v, 64); err == nil {
-			return v2
-		}
-	}
-	return defaultValue
+	return Object(key, defaultValue, ConvertComplex128)
+}
+
+func Complex64(key string, defaultValue complex64) complex64 {
+	return Object(key, defaultValue, ConvertComplex64)
 }
 
 func Bool(key string, defaultValue bool) bool {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := strconv.ParseBool(v); err == nil {
-			return v2
-		}
-	}
-	return defaultValue
+	return Object(key, defaultValue, ConvertBool)
 }
 
-func Object[T any](key string, defaultValue T, converter func(string) (T, error)) T {
-	if v, ok := os.LookupEnv(key); ok {
-		if v2, err := converter(v); err == nil {
-			return v2
-		}
-	}
-	return defaultValue
+func Time(key string, defaultValue time.Time, layout string) time.Time {
+	return Object(key, defaultValue, func(s string) (time.Time, error) { return time.Parse(layout, s) })
+}
+
+func Duration(key string, defaultValue time.Duration) time.Duration {
+	return Object(key, defaultValue, time.ParseDuration)
 }