# `•prefs` — Display settings

`•prefs Y` applies the settings in the record `Y` to this session’s
display, and returns every setting. `•prefs ⍬` changes nothing.

<table>
<colgroup>
<col style="width: 33%" />
<col style="width: 33%" />
<col style="width: 33%" />
</colgroup>
<thead>
<tr>
<th>Setting</th>
<th>Holds</th>
<th>Default</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>box</code></td>
<td><code>$t</code> draws arrays in boxes</td>
<td><code>$t</code> in the REPL and the BPL Jupyter kernel,
<code>$f</code> elsewhere</td>
</tr>
<tr>
<td><code>trees</code></td>
<td><code>$t</code> shows functions and dissected expressions as trees;
<code>$f</code> uses linear notation. Independent of
<code>box</code></td>
<td>as <code>box</code></td>
</tr>
<tr>
<td><code>fns</code></td>
<td><code>$f</code> leaves output made inside functions unboxed</td>
<td>as <code>box</code></td>
</tr>
<tr>
<td><code>dissect</code></td>
<td><code>$t</code> shows the bound expression before each normal
result, using <code>trees</code></td>
<td><code>$f</code></td>
</tr>
<tr>
<td><code>limit</code></td>
<td>The most items display shows in full. <code>∞</code> shows every
item</td>
<td><code>1000</code></td>
</tr>
<tr>
<td><code>edges</code></td>
<td>Positions shown at each end of a long axis</td>
<td><code>3</code></td>
</tr>
<tr>
<td><code>prec</code></td>
<td>Significant digits shown for each float. <code>∞</code> shows every
digit</td>
<td><code>10</code></td>
</tr>
<tr>
<td><code>width</code></td>
<td>The widest line display shows. <code>∞</code> allows any width</td>
<td>The terminal’s width in the REPL, <code>∞</code> elsewhere</td>
</tr>
</tbody>
</table>

Display shows part of an array of more than `limit` items: the first and
last `edges` positions of each axis longer than twice `edges`. `…`
replaces the hidden columns, `⋮` the hidden rows, and `⋱` sits where
they cross. A nested array follows the same rule on its own. A line
wider than `width` hides columns in the same way, keeping as many at
each end as fit. `⎕←` always shows every item, and rounds floats to
`prec` as display does. [`⍕`](../glyphs/format.qmd) and source text
always hold every item and every digit.

Errors: `DOMAIN` for an unknown setting or an invalid value.