diff --git a/Cargo.lock b/Cargo.lock
index 8854206..3ca555c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -67,7 +67,7 @@ checksum = "06ea2b9bc92be3c2baa9334a323ebca2d6f074ff852cd1d7b11064035cd3868f"
 
 [[package]]
 name = "fsrs"
-version = "0.4.0"
+version = "1.0.0"
 dependencies = [
  "chrono",
  "serde",
diff --git a/src/lib.rs b/src/lib.rs
index 4bad2ca..78aa403 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -11,7 +11,7 @@ mod scheduler_longterm;
 pub use scheduler_longterm::LongtermScheduler;
 
 mod models;
-pub use models::{Card, Rating, ReviewLog, SchedulingInfo, State};
+pub use models::{Card, Rating, RecordLog, ReviewLog, SchedulingInfo, State};
 
 mod parameters;
 pub use crate::parameters::Parameters;
diff --git a/src/scheduler.rs b/src/scheduler.rs
index a47848b..3d661ba 100644
--- a/src/scheduler.rs
+++ b/src/scheduler.rs
@@ -47,11 +47,9 @@ impl Scheduler {
 
 pub trait ImplScheduler {
     fn preview(&mut self) -> RecordLog {
-        let mut log = RecordLog::new();
-        for rating in Rating::iter() {
-            log.insert(*rating, self.review(*rating));
-        }
-        log
+        Rating::iter()
+            .map(|&rating| (rating, self.review(rating)))
+            .collect()
     }
     fn review(&mut self, rating: Rating) -> SchedulingInfo;
 }