Crate tinyvec

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tinyvec provides 100% safe vec-like data structures.

§Provided Types

With no features enabled, this crate provides the ArrayVec type, which is an array-backed storage. You can push values into the array and pop them out of the array and so on. If the array is made to overflow it will panic.

Similarly, there is also a SliceVec type available, which is a vec-like that’s backed by a slice you provide. You can add and remove elements, but if you overflow the slice it will panic.

With the alloc feature enabled, the crate also has a TinyVec type. This is an enum type which is either an Inline(ArrayVec) or a Heap(Vec). If a TinyVec is Inline and would overflow it automatically transitions itself into being Heap mode instead of a panic.

All of this is done with no unsafe code within the crate. Technically the Vec type from the standard library uses unsafe internally, but this crate introduces no new unsafe code into your project.

The limitation is that the element type of a vec from this crate must support the Default trait. This means that this crate isn’t suitable for all situations, but a very surprising number of types do support Default.

§Other Features

  • grab_spare_slice lets you get access to the “inactive” portions of an ArrayVec.
  • rustc_1_40 makes the crate assume a minimum rust version of 1.40.0, which allows some better internal optimizations.
  • serde provides a Serialize and Deserialize implementation for TinyVec and ArrayVec types, provided the inner item also has an implementation.


The general goal of the crate is that, as much as possible, the vecs here should be a “drop in” replacement for the standard library Vec type. We strive to provide all of the Vec methods with the same names and signatures. The exception is that the element type of some methods will have a Default bound that’s not part of the normal Vec type.

The vecs here also have a few additional methods that aren’t on the Vec type. In this case, the names tend to be fairly long so that they are unlikely to clash with any future methods added to Vec.


  • The 1.0 series of the crate works with Rustc 1.34.0 or later, though you still need to have Rustc 1.36.0 to use the alloc feature.
  • The 2.0 version of the crate is planned for some time after the min_const_generics stuff becomes stable. This would greatly raise the minimum rust version and also allow us to totally eliminate the need for the Array trait. The actual usage of the crate is not expected to break significantly in this transition.




  • A vector that starts inline, but can automatically move to the heap.
  • Draining iterator for TinyVecDrain
  • Iterator for consuming an TinyVec and returning owned elements.


  • A trait for types that are an array.