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+# Pulling `Result`s out of `Option`s
+
+The most basic way of handling mixed error types is to just embed them in each
+other.
+
+```rust,editable
+use std::num::ParseIntError;
+
+fn double_first(vec: Vec<&str>) -> Option<Result<i32, ParseIntError>> {
+    vec.first().map(|first| {
+        first.parse::<i32>().map(|n| 2 * n)
+    })
+}
+
+fn main() {
+    let numbers = vec!["42", "93", "18"];
+    let empty = vec![];
+    let strings = vec!["tofu", "93", "18"];
+
+    println!("The first doubled is {:?}", double_first(numbers));
+
+    println!("The first doubled is {:?}", double_first(empty));
+    // Error 1: the input vector is empty
+
+    println!("The first doubled is {:?}", double_first(strings));
+    // Error 2: the element doesn't parse to a number
+}
+```
+
+There are times when we'll want to stop processing on errors (like with
+[`?`][enter_question_mark]) but keep going when the `Option` is `None`. A
+couple of combinators come in handy to swap the `Result` and `Option`.
+
+```rust,editable
+use std::num::ParseIntError;
+
+fn double_first(vec: Vec<&str>) -> Result<Option<i32>, ParseIntError> {
+    let opt = vec.first().map(|first| {
+        first.parse::<i32>().map(|n| 2 * n)
+    });
+
+    opt.map_or(Ok(None), |r| r.map(Some))
+}
+
+fn main() {
+    let numbers = vec!["42", "93", "18"];
+    let empty = vec![];
+    let strings = vec!["tofu", "93", "18"];
+
+    println!("The first doubled is {:?}", double_first(numbers));
+    println!("The first doubled is {:?}", double_first(empty));
+    println!("The first doubled is {:?}", double_first(strings));
+}
+```
+
+[enter_question_mark]: ../result/enter_question_mark.md