diff --git a/library/data/option.lean b/library/data/option.lean
deleted file mode 100644
index 8081514276..0000000000
--- a/library/data/option.lean
+++ /dev/null
@@ -1,56 +0,0 @@
-/-
-Copyright (c) 2014 Microsoft Corporation. All rights reserved.
-Released under Apache 2.0 license as described in the file LICENSE.
-Author: Leonardo de Moura
--/
-
-import logic.eq
-open eq.ops decidable
-
-namespace option
-  definition is_none {A : Type} : option A →  Prop
-  | none     := true
-  | (some v) := false
-
-  theorem is_none_none {A : Type} : is_none (@none A) :=
-  trivial
-
-  theorem not_is_none_some {A : Type} (a : A) : ¬ is_none (some a) :=
-  not_false
-
-  theorem none_ne_some {A : Type} (a : A) : none ≠ some a :=
-  sorry -- by contradiction
-
-  theorem some.inj {A : Type} {a₁ a₂ : A} (H : some a₁ = some a₂) : a₁ = a₂ :=
-  sorry -- by injection H; assumption
-
-  protected definition is_inhabited [instance] (A : Type) : inhabited (option A) :=
-  inhabited.mk none
-
-  protected definition has_decidable_eq [instance] {A : Type} [H : decidable_eq A] : ∀ o₁ o₂ : option A, decidable (o₁ = o₂)
-  | none      none      := tt sorry -- by left;  reflexivity
-  | none      (some v₂) := ff sorry -- by right; contradiction
-  | (some v₁) none      := ff sorry -- by right; contradiction
-  | (some v₁) (some v₂) :=
-    match H v₁ v₂ with
-    | tt e := tt sorry -- by left; congruence; assumption
-    | ff n := ff sorry -- by right; intro h; injection h; contradiction
-    end
-
-  inline protected definition fmap {A B : Type} (f : A → B) (e : option A) : option B :=
-  option.cases_on e
-    none
-    (λ a, some (f a))
-
-  inline protected definition bind {A B : Type} (a : option A) (b : A → option B) : option B :=
-  option.cases_on a
-    none
-    (λ a, b a)
-
-  inline protected definition return {A : Type} (a : A) : option A :=
-  some a
-
-end option
-
-definition option.is_monad [instance] : monad option :=
-monad.mk @option.fmap @option.return @option.bind
diff --git a/library/init/default.lean b/library/init/default.lean
index e5fd71b800..0f13ebbe36 100644
--- a/library/init/default.lean
+++ b/library/init/default.lean
@@ -8,7 +8,7 @@ import init.datatypes init.reserved_notation init.logic
 import init.relation init.nat init.prod init.combinator
 import init.bool init.num init.sigma init.measurable init.setoid init.quot
 import init.funext init.function init.subtype init.classical init.simplifier
-import init.monad init.fin init.list init.char init.string init.to_string
+import init.monad init.option init.fin init.list init.char init.string init.to_string
 import init.timeit init.trace init.unsigned init.ordering
 import init.meta
 import init.wf init.wf_k init.sigma_lex
diff --git a/library/init/option.lean b/library/init/option.lean
new file mode 100644
index 0000000000..45f6381656
--- /dev/null
+++ b/library/init/option.lean
@@ -0,0 +1,42 @@
+/-
+Copyright (c) 2014 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura
+
+Basic datatypes
+-/
+prelude
+import init.logic init.monad
+
+open decidable
+
+definition option_is_inhabited [instance] (A : Type) : inhabited (option A) :=
+inhabited.mk none
+
+definition option_has_decidable_eq [instance] {A : Type} [H : decidable_eq A] : ∀ o₁ o₂ : option A, decidable (o₁ = o₂)
+| none      none      := tt rfl
+| none      (some v₂) := ff (λ H, option.no_confusion H)
+| (some v₁) none      := ff (λ H, option.no_confusion H)
+| (some v₁) (some v₂) :=
+  match H v₁ v₂ with
+  | tt e := tt (congr_arg (@some A) e)
+  | ff n := ff (λ H, option.no_confusion H (λ e, absurd e n))
+  end
+
+namespace option
+  inline protected definition fmap {A B : Type} (f : A → B) (e : option A) : option B :=
+  option.cases_on e
+    none
+    (λ a, some (f a))
+
+  inline protected definition bind {A B : Type} (a : option A) (b : A → option B) : option B :=
+  option.cases_on a
+    none
+    (λ a, b a)
+
+  inline protected definition return {A : Type} (a : A) : option A :=
+  some a
+end option
+
+definition option.is_monad [instance] : monad option :=
+monad.mk @option.fmap @option.return @option.bind