add native option type

book/src/super-sql/functions/types/upcast.md

@@ -42,7 +42,7 @@ values
 
 # expected output
 {x:1,y?:none::string}
-{x:1,y?:none::(string|null|none)}
+{x:1,y?:none::option(string|null)}
 ```
 
 ---

book/src/super-sql/operators/fuse.md

@@ -36,8 +36,8 @@ fuse
 {a:1}
 {b:2}
 # expected output
-fusion({a:fusion(1::(int64|none),<int64>),b:fusion(none::(int64|none),<none>)},<{a:int64}>)
-fusion({a:fusion(none::(int64|none),<none>),b:fusion(2::(int64|none),<int64>)},<{b:int64}>)
+fusion({a:fusion(some(1),<int64>),b:fusion(none::int64,<none>)},<{a:int64}>)
+fusion({a:fusion(none::int64,<none>),b:fusion(some(2),<int64>)},<{b:int64}>)
 ```
 
 ---
@@ -64,6 +64,6 @@ fuse
 {a:[1,2]}
 {a:["foo","bar"],b:10.0.0.1}
 # expected output
-fusion({a:fusion([fusion(1::(int64|string),<int64>),fusion(2::(int64|string),<int64>)],<[int64]>),b:fusion(none::(ip|none),<none>)},<{a:[int64]}>)
-fusion({a:fusion([fusion("foo"::(int64|string),<string>),fusion("bar"::(int64|string),<string>)],<[string]>),b:fusion(10.0.0.1::(ip|none),<ip>)},<{a:[string],b:ip}>)
+fusion({a:fusion([fusion(1::(int64|string),<int64>),fusion(2::(int64|string),<int64>)],<[int64]>),b:fusion(none::ip,<none>)},<{a:[int64]}>)
+fusion({a:fusion([fusion("foo"::(int64|string),<string>),fusion("bar"::(int64|string),<string>)],<[string]>),b:fusion(some(10.0.0.1),<ip>)},<{a:[string],b:ip}>)
 ```

compiler/ast/type.go

@@ -58,6 +58,11 @@ type (
 		Type Type   `json:"type"`
 		Loc  `json:"loc"`
 	}
+	TypeOption struct {
+		Kind string `json:"kind" unpack:""`
+		Type Type   `json:"type"`
+		Loc  `json:"loc"`
+	}
 	TypeRef struct {
 		Kind string `json:"kind" unpack:""`
 		Name string `json:"name"`
@@ -74,6 +79,7 @@ func (*TypeEnum) typeNode()      {}
 func (*TypeMap) typeNode()       {}
 func (*TypeError) typeNode()     {}
 func (*TypeFusion) typeNode()    {}
+func (*TypeOption) typeNode()    {}
 func (*TypeRef) typeNode()       {}
 
 // This is a hack that allows us to express a "date" type until we

compiler/ast/value.go

@@ -69,6 +69,10 @@ type (
 		Value Value      `json:"value"`
 		Type  *TypeValue `json:"type"`
 	}
+	Some struct {
+		Kind  string `json:"kind" unpack:""`
+		Value Value  `json:"value"`
+	}
 	None struct {
 		Kind string `json:"kind" unpack:""`
 		Type Type   `json:"type"`
@@ -83,6 +87,7 @@ func (*Map) valueNode()             {}
 func (*TypeValue) valueNode()       {}
 func (*Error) valueNode()           {}
 func (*Fusion) valueNode()          {}
+func (*Some) valueNode()            {}
 func (*None) valueNode()            {}
 func (*DoubleQuoteExpr) valueNode() {}