diff --git a/attribute/generated.go b/attribute/generated.go
index 3cd3333..8e0c05b 100644
--- a/attribute/generated.go
+++ b/attribute/generated.go
@@ -9,7 +9,7 @@ import "gitlab.codemonkeysoftware.net/b/hatmill"
 func Accept(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "accept",
-		Value: String(CommaList(value).String()),
+		Value: CommaList(value),
 	}
 }
 
@@ -17,7 +17,7 @@ func Accept(value ...string) hatmill.Attrib {
 func AcceptCharset(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "accept-charset",
-		Value: String(SpaceList(value).String()),
+		Value: SpaceList(value),
 	}
 }
 
@@ -101,7 +101,7 @@ func Cite(value string) hatmill.Attrib {
 func Class(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "class",
-		Value: String(SpaceList(value).String()),
+		Value: SpaceList(value),
 	}
 }
 
@@ -109,7 +109,7 @@ func Class(value ...string) hatmill.Attrib {
 func Cols(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "cols",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -117,7 +117,7 @@ func Cols(value int) hatmill.Attrib {
 func Colspan(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "colspan",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -133,7 +133,7 @@ func Content(value string) hatmill.Attrib {
 func Contenteditable(value bool) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "contenteditable",
-		Value: String(Bool(value).String()),
+		Value: Bool(value),
 	}
 }
 
@@ -225,7 +225,7 @@ func Download(value string) hatmill.Attrib {
 func Draggable(value bool) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "draggable",
-		Value: String(Bool(value).String()),
+		Value: Bool(value),
 	}
 }
 
@@ -241,7 +241,7 @@ func Enctype(value string) hatmill.Attrib {
 func For(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "for",
-		Value: String(SpaceList(value).String()),
+		Value: SpaceList(value),
 	}
 }
 
@@ -273,7 +273,7 @@ func Formmethod(value string) hatmill.Attrib {
 func Headers(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "headers",
-		Value: String(SpaceList(value).String()),
+		Value: SpaceList(value),
 	}
 }
 
@@ -281,7 +281,7 @@ func Headers(value ...string) hatmill.Attrib {
 func Height(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "height",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -296,7 +296,7 @@ func Hidden() hatmill.Attrib {
 func High(value float32) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "high",
-		Value: String(Float(value).String()),
+		Value: Float(value),
 	}
 }
 
@@ -390,7 +390,7 @@ func Loop() hatmill.Attrib {
 func Low(value float32) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "low",
-		Value: String(Float(value).String()),
+		Value: Float(value),
 	}
 }
 
@@ -398,7 +398,7 @@ func Low(value float32) hatmill.Attrib {
 func Max(value float32) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "max",
-		Value: String(Float(value).String()),
+		Value: Float(value),
 	}
 }
 
@@ -406,7 +406,7 @@ func Max(value float32) hatmill.Attrib {
 func Maxlength(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "maxlength",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -430,7 +430,7 @@ func Method(value string) hatmill.Attrib {
 func Min(value float32) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "min",
-		Value: String(Float(value).String()),
+		Value: Float(value),
 	}
 }
 
@@ -438,7 +438,7 @@ func Min(value float32) hatmill.Attrib {
 func Minlength(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "minlength",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -482,7 +482,7 @@ func Open() hatmill.Attrib {
 func Optimum(value float32) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "optimum",
-		Value: String(Float(value).String()),
+		Value: Float(value),
 	}
 }
 
@@ -498,7 +498,7 @@ func Pattern(value string) hatmill.Attrib {
 func Ping(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "ping",
-		Value: String(SpaceList(value).String()),
+		Value: SpaceList(value),
 	}
 }
 
@@ -545,7 +545,7 @@ func Referrerpolicy(value string) hatmill.Attrib {
 func Rel(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "rel",
-		Value: String(SpaceList(value).String()),
+		Value: SpaceList(value),
 	}
 }
 
@@ -567,7 +567,7 @@ func Reversed() hatmill.Attrib {
 func Rows(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "rows",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -575,7 +575,7 @@ func Rows(value int) hatmill.Attrib {
 func Rowspan(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "rowspan",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -583,7 +583,7 @@ func Rowspan(value int) hatmill.Attrib {
 func Sandbox(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "sandbox",
-		Value: String(SpaceList(value).String()),
+		Value: SpaceList(value),
 	}
 }
 
@@ -614,7 +614,7 @@ func Shape(value string) hatmill.Attrib {
 func Size(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "size",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -630,7 +630,7 @@ func Sizes(value string) hatmill.Attrib {
 func Span(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "span",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -638,7 +638,7 @@ func Span(value int) hatmill.Attrib {
 func Spellcheck(value bool) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "spellcheck",
-		Value: String(Bool(value).String()),
+		Value: Bool(value),
 	}
 }
 
@@ -670,7 +670,7 @@ func Srclang(value string) hatmill.Attrib {
 func Srcset(value ...string) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "srcset",
-		Value: String(CommaList(value).String()),
+		Value: CommaList(value),
 	}
 }
 
@@ -694,7 +694,7 @@ func Style(value string) hatmill.Attrib {
 func Tabindex(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "tabindex",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
@@ -742,7 +742,7 @@ func Value(value string) hatmill.Attrib {
 func Width(value int) hatmill.Attrib {
 	return hatmill.Attrib{
 		Key:   "width",
-		Value: String(Int(value).String()),
+		Value: Int(value),
 	}
 }
 
diff --git a/attribute/generated_test.go b/attribute/generated_test.go
index 4a9fef0..6352821 100644
--- a/attribute/generated_test.go
+++ b/attribute/generated_test.go
@@ -14,11 +14,6 @@ func testAttribValue(t *testing.T, attrib hatmill.Attrib, expectedValue string)
 	}
 }
 
-func TestString(t *testing.T) {
-	const s = "abcdefg"
-	testAttribValue(t, attribute.Id(s), s)
-}
-
 func TestBool(t *testing.T) {
 	testAttribValue(t, attribute.Disabled(), "")
 }
diff --git a/attribute/string.go b/attribute/string.go
deleted file mode 100644
index 8eb46fe..0000000
--- a/attribute/string.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package attribute
-
-type String string
-
-func (s String) String() string {
-	return string(s)
-}
diff --git a/attribute/value_types.go b/attribute/value_types.go
index 001b49e..84ad47f 100644
--- a/attribute/value_types.go
+++ b/attribute/value_types.go
@@ -32,3 +32,9 @@ type Bool bool
 func (b Bool) String() string {
 	return strconv.FormatBool(bool(b))
 }
+
+type String string
+
+func (s String) String() string {
+	return string(s)
+}
diff --git a/attribute/value_types_test.go b/attribute/value_types_test.go
index d2adf31..38b46de 100644
--- a/attribute/value_types_test.go
+++ b/attribute/value_types_test.go
@@ -76,3 +76,8 @@ func TestExplicitBool(t *testing.T) {
 		expectEqualStrings(t, attribute.Bool(false).String(), "false")
 	})
 }
+
+func TestString(t *testing.T) {
+	const s = "abcdefg"
+	expectEqualStrings(t, attribute.String(s).String(), s)
+}
diff --git a/internal/codegen/codegen.go b/internal/codegen/codegen.go
index 3cc2c8d..3f6f54c 100644
--- a/internal/codegen/codegen.go
+++ b/internal/codegen/codegen.go
@@ -20,54 +20,55 @@ func identifier(s string) string {
 }
 
 type AttribTypeInfo struct {
-	Template string
+	Template AttribTemplate
 }
 
-func simpleTemplate(paramType, convertExpr string) string {
-	conversion := fmt.Sprintf(convertExpr, "value")
-	return fmt.Sprintf(`func %%s(value %s) hatmill.Attrib {
-		return hatmill.Attrib{
-			Key: "%%s",
-			Value: String(%s),
-		}
+type AttribTemplate func(identifier, name string) string
+
+func simpleTemplate(paramType, toType string) AttribTemplate {
+	return func(identifier, name string) string {
+		return fmt.Sprintf(
+			`func %s(value %s) hatmill.Attrib {
+				return hatmill.Attrib{
+					Key: "%s",
+					Value: %s(value),
+				}
+			}
+			`, identifier, paramType, name, toType)
 	}
-	`, paramType, conversion)
 }
 
-func listTemplate(separator string) string {
-	return fmt.Sprintf(`func %%s(value ...string) hatmill.Attrib {
-		return hatmill.Attrib{
-			Key: "%%s",
-			Value: String(strings.Join(value, "%s")),
-		}
-	}
-	`, separator)
-}
-
-var attribTypes = map[string]AttribTypeInfo{
-	"string": {Template: simpleTemplate("string", "%s")},
-	"bool": {
-		Template: `func %s() hatmill.Attrib {
+func boolTemplate(identifier, name string) string {
+	return fmt.Sprintf(
+		`func %s() hatmill.Attrib {
 			return hatmill.Attrib{
 				Key: "%s",
 			}
 		}
-		`,
+		`, identifier, name)
+}
+
+var attribTypes = map[string]AttribTypeInfo{
+	"string": {
+		Template: simpleTemplate("string", "String"),
+	},
+	"bool": {
+		Template: boolTemplate,
 	},
 	"explicit bool": {
-		Template: simpleTemplate("bool", "Bool(%s).String()"),
+		Template: simpleTemplate("bool", "Bool"),
 	},
 	"int": {
-		Template: simpleTemplate("int", "Int(%s).String()"),
+		Template: simpleTemplate("int", "Int"),
 	},
 	"float": {
-		Template: simpleTemplate("float32", "Float(%s).String()"),
+		Template: simpleTemplate("float32", "Float"),
 	},
 	"space list": {
-		Template: simpleTemplate("...string", "SpaceList(%s).String()"),
+		Template: simpleTemplate("...string", "SpaceList"),
 	},
 	"comma list": {
-		Template: simpleTemplate("...string", "CommaList(%s).String()"),
+		Template: simpleTemplate("...string", "CommaList"),
 	},
 }
 
@@ -91,7 +92,7 @@ func (spec AttribSpec) Generate() Def {
 	comment := fmt.Sprintf("// %s creates a \"%s\" attribute\n", ident, name)
 	template := attribTypes[spec.Type].Template
 	return Def{
-		Source: comment + fmt.Sprintf(template, ident, name),
+		Source: comment + template(ident, name),
 	}
 }