ExpressionType:
    | {
        name: string;
        type: "column";
    }
    | {
        type: "literal";
        value: FilterValue;
    }
    | {
        args: ExpressionType[];
        name: string;
        type: "function";
    }
    | {
        sql: string;
        type: "raw";
    }

Structured expression type