diff --git a/README.md b/README.md
index 8610d4b..958c47e 100644
--- a/README.md
+++ b/README.md
@@ -46,15 +46,6 @@ dater$> 2021 11 12 - 2022 1 1
 0/1/20
 ```
 
-### Today
-
-Let today be November 12th, 2021.
-Then, in action, we have:
-```
-dater$> today + day(5)
-2021/11/7
-```
-
 # Usage
 The recommended way to use the language is with the toplevel interpreter in this repository.
 
diff --git a/package.yaml b/package.yaml
index 1d8999e..606ceae 100644
--- a/package.yaml
+++ b/package.yaml
@@ -1,5 +1,5 @@
 name:                dater
-version:             0.1.0.0
+version:             1.0.0
 github:              "wonhyukchoi/dater"
 license:             MIT
 author:              "Wonhyuk Choi"
diff --git a/src/Parser.hs b/src/Parser.hs
index 1e947ff..b568c43 100644
--- a/src/Parser.hs
+++ b/src/Parser.hs
@@ -12,6 +12,8 @@ import Control.Applicative((<|>))
 import Text.Parsec.String(Parser)
 import Text.Parsec(try)
 
+import Data.Time
+
 import qualified Text.Parsec as Parsec
 import qualified Text.Parsec.Expr as Ex
 import qualified Text.Parsec.Token as Tok