Printing - SOS 1.9
Description: SOS 1.9

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## 6 Printing

The following procedures can be used to define a custom printed representation for an instance. It is highly recommended that instances be printed by `write-instance-helper`, as this ensures a uniform appearance for all objects.

— Generic Procedure: write-instance instance port

> This is called by the runtime system to generate the printed representation of instance. The methods of this procedure should write the representation to port.

— Procedure: write-instance-helper name instance port thunk

> This writes a standardized “frame” for a printed representation method. It generates the following output on port:

>               #[name hash-number...]

> where hash-number is the result of calling `hash` on instance, and ... is the output generated by thunk.