Known Issues and Workarounds

Known Issues

  • #1663: Using an explicit return in all branches of an if let expression causes a compile error. The workaround is to use implicit returns instead.

  • #1387: In order to use unwrap() from the result library, all symbols of result needs to be imported via use::result::*;.

  • #870: All impl blocks need to be defined before any of the functions they define can be called.

Missing Features

  • #1182 Arrays in a storage block are not yet supported. See the Manual Storage Management section for details on how to use store and get from the standard library to manage storage slots directly. Note, however, that StorageMap<K, V> does support arbitrary types for K and V without any limitations.

  • #428: Arrays are currently immutable which means that changing elements of an array once initialized is not yet possible.

  • #1077: Dynamic vectors, i.e. Vec<T>, have not yet been implemented.


  • No compiler optimization passes have been implemented yet, therefore bytecode will be more expensive and larger than it would be in production. Note that eventually the optimizer will support zero-cost abstractions, avoiding the need for developers to go down to inline assembly to produce optimal code.

  • Currently, we need to parse the Sway code before formatting it. Hence, the formatter cannot work on Sway code that does not parse correctly. This requirement may be changed in the future.