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*print-miser-width*

∗print-miser-width∗ Variable

Value Type:

a non-negative integer , or nil.

Initial Value:

implementation-dependent

Description:

If it is not nil, the pretty printer switches to a compact style of output (called miser style) whenever the width available for printing a substructure is less than or equal to this many ems.

Expanded Reference: *print-miser-width*​

What Is Miser Mode​

Miser mode is a compact pretty-printing style that is activated when the available width for printing a substructure is less than or equal to *print-miser-width* ems. In miser mode, fill-style conditional newlines act like linear-style newlines, resulting in more line breaks.

;; With a narrow right margin and miser-width, miser mode kicks in
(let ((*print-pretty* t)
      (*print-right-margin* 30)
      (*print-miser-width* 20))
  (write-to-string '(let ((a 1) (b 2)) (+ a b))))
=> "(LET ((A 1) (B 2))
  (+ A B))"

Disabling Miser Mode​

When *print-miser-width* is nil, miser mode is never activated.

(let ((*print-pretty* t)
      (*print-right-margin* 40)
      (*print-miser-width* nil))
  (write-to-string '(let ((a 1) (b 2) (c 3)) (+ a b c))))
=> "(LET ((A 1) (B 2) (C 3))
  (+ A B C))"

Miser Mode Ignores pprint-indent​

In miser mode, all calls to pprint-indent are ignored, and lines within a logical block are aligned under the first character of the block.

;; When miser mode is active, indentation changes are suppressed
;; and output is as compact as possible