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7.5.2 Quick Print

(require 'qp)

When displaying error messages and warnings, it is paramount that the output generated for circular lists and large data structures be limited. This section supplies a procedure to do this. It could be much improved.

Notice that the neccessity for truncating output eliminates Common-Lisp’s Format from consideration; even when variables *print-level* and *print-level* are set, huge strings and bit-vectors are not limited.

Procedure: qp arg1 …
Procedure: qpn arg1 …
Procedure: qpr arg1 …

qp writes its arguments, separated by spaces, to (current-output-port). qp compresses printing by substituting ‘...’ for substructure it does not have sufficient room to print. qpn is like qp but outputs a newline before returning. qpr is like qpn except that it returns its last argument.

Variable: *qp-width*

*qp-width* is the largest number of characters that qp should use. If *qp-width* is #f, then all items will be writen. If *qp-width* is 0, then all items except procedures will be writen; procedures will be indicated by ‘#[proc]’.