From perldoc perldata: 
String literals are usually delimited by either single or double
quotes.  They work much like quotes in the standard Unix shells: dou-
ble-quoted string literals are subject to backslash and variable sub-
stitution; single-quoted strings are not (except for "\'" and "\\").

[download]
The allowed backslash substitutions are self-explanatory: although people would better use alternate delimiters, it is apparent that for completeness and consistency the possibility of backslashing "'" is given, and once that is provided, it is obvious that the backslash itself needs a backslash substitution as well.

In reply to Re: Interpolation between single quotes? by blazar
in thread Interpolation between single quotes? by esharris

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.