Std.Sync.swap

fn

This is a callable function.

What it does

Replace what a cell holds and answer what it held, in one step nothing can

come between.

This is the only write, because it is the only one that composes. A read

followed by a write is two steps, and another thread can act between them:

a counter built that way loses additions, and loses them only under the

load that makes the loss hardest to reproduce. A caller that needs to

decide what to write from what is there wants Counter or a lock.

Read the signature

• The text after the name is the type checked by Pudu.
• Read arrows from left to right: inputs come first, and the final type is returned.
• & borrows a value for this call instead of moving or copying it.
• Names inside [ ] are type arguments, such as the item type held by a collection.
• Result makes success and recoverable failure part of the function's type.