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| -rw-r--r-- | src/doc/trpl/iterators.md | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/src/doc/trpl/iterators.md b/src/doc/trpl/iterators.md index 1a5f7bf9959..ce0283480c6 100644 --- a/src/doc/trpl/iterators.md +++ b/src/doc/trpl/iterators.md @@ -132,7 +132,16 @@ let one_to_one_hundred = (1..101i32).collect::<Vec<i32>>(); ``` If you remember, the `::<>` syntax allows us to give a type hint, -and so we tell it that we want a vector of integers. +and so we tell it that we want a vector of integers. You don't always +need to use the whole type, though. Using a `_` will let you provide +a partial hint: + +```rust +let one_to_one_hundred = range(1, 101).collect::<Vec<_>>(); +``` + +This says "Collect into a `Vec<T>`, please, but infer what the `T` is for me." +`_` is sometimes called a "type placeholder" for this reason. `collect()` is the most common consumer, but there are others too. `find()` is one: |