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<title>SRFI-19 Time (Guile Reference Manual)</title>
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<div class="subsubsection-level-extent" id="SRFI_002d19-Time">
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<p>
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Next: <a href="SRFI_002d19-Date.html" accesskey="n" rel="next">SRFI-19 Date</a>, Previous: <a href="SRFI_002d19-Introduction.html" accesskey="p" rel="prev">SRFI-19 Introduction</a>, Up: <a href="SRFI_002d19.html" accesskey="u" rel="up">SRFI-19 - Time/Date Library</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
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<h4 class="subsubsection" id="SRFI_002d19-Time-1"><span>7.5.16.2 SRFI-19 Time<a class="copiable-link" href="#SRFI_002d19-Time-1"> ¶</a></span></h4>
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<a class="index-entry-id" id="index-time-2"></a>
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<p>A <em class="dfn">time</em> object has type, seconds and nanoseconds fields
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representing a point in time starting from some epoch. This is an
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arbitrary point in time, not just a time of day. Although times are
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represented in nanoseconds, the actual resolution may be lower.
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</p>
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<p>The following variables hold the possible time types. For instance
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<code class="code">(current-time time-process)</code> would give the current CPU process
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time.
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</p>
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<dl class="first-defvr first-defvar-alias-first-defvr">
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<dt class="defvr defvar-alias-defvr" id="index-time_002dutc"><span class="category-def">Variable: </span><span><strong class="def-name">time-utc</strong><a class="copiable-link" href="#index-time_002dutc"> ¶</a></span></dt>
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<dd><p>Universal Coordinated Time (UTC).
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<a class="index-entry-id" id="index-UTC-1"></a>
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</p></dd></dl>
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<dl class="first-defvr first-defvar-alias-first-defvr">
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<dt class="defvr defvar-alias-defvr" id="index-time_002dtai"><span class="category-def">Variable: </span><span><strong class="def-name">time-tai</strong><a class="copiable-link" href="#index-time_002dtai"> ¶</a></span></dt>
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<dd><p>International Atomic Time (TAI).
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<a class="index-entry-id" id="index-TAI-1"></a>
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</p></dd></dl>
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<dl class="first-defvr first-defvar-alias-first-defvr">
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<dt class="defvr defvar-alias-defvr" id="index-time_002dmonotonic"><span class="category-def">Variable: </span><span><strong class="def-name">time-monotonic</strong><a class="copiable-link" href="#index-time_002dmonotonic"> ¶</a></span></dt>
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<dd><p>Monotonic time, meaning a monotonically increasing time starting from
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an unspecified epoch.
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</p>
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<p>Note that in the current implementation <code class="code">time-monotonic</code> is the
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same as <code class="code">time-tai</code>, and unfortunately is therefore affected by
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adjustments to the system clock. Perhaps this will change in the
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future.
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</p></dd></dl>
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<dl class="first-defvr first-defvar-alias-first-defvr">
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<dt class="defvr defvar-alias-defvr" id="index-time_002dduration"><span class="category-def">Variable: </span><span><strong class="def-name">time-duration</strong><a class="copiable-link" href="#index-time_002dduration"> ¶</a></span></dt>
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<dd><p>A duration, meaning simply a difference between two times.
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</p></dd></dl>
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<dl class="first-defvr first-defvar-alias-first-defvr">
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<dt class="defvr defvar-alias-defvr" id="index-time_002dprocess"><span class="category-def">Variable: </span><span><strong class="def-name">time-process</strong><a class="copiable-link" href="#index-time_002dprocess"> ¶</a></span></dt>
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<dd><p>CPU time spent in the current process, starting from when the process
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began.
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<a class="index-entry-id" id="index-process-time"></a>
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</p></dd></dl>
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<dl class="first-defvr first-defvar-alias-first-defvr">
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<dt class="defvr defvar-alias-defvr" id="index-time_002dthread"><span class="category-def">Variable: </span><span><strong class="def-name">time-thread</strong><a class="copiable-link" href="#index-time_002dthread"> ¶</a></span></dt>
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<dd><p>CPU time spent in the current thread. Not currently implemented.
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<a class="index-entry-id" id="index-thread-time"></a>
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</p></dd></dl>
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<br>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-time_003f-1"><span class="category-def">Function: </span><span><strong class="def-name">time?</strong> <var class="def-var-arguments">obj</var><a class="copiable-link" href="#index-time_003f-1"> ¶</a></span></dt>
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<dd><p>Return <code class="code">#t</code> if <var class="var">obj</var> is a time object, or <code class="code">#f</code> if not.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-make_002dtime"><span class="category-def">Function: </span><span><strong class="def-name">make-time</strong> <var class="def-var-arguments">type nanoseconds seconds</var><a class="copiable-link" href="#index-make_002dtime"> ¶</a></span></dt>
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<dd><p>Create a time object with the given <var class="var">type</var>, <var class="var">seconds</var> and
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<var class="var">nanoseconds</var>.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-time_002dtype"><span class="category-def">Function: </span><span><strong class="def-name">time-type</strong> <var class="def-var-arguments">time</var><a class="copiable-link" href="#index-time_002dtype"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-time_002dnanosecond"><span class="category-def">Function: </span><span><strong class="def-name">time-nanosecond</strong> <var class="def-var-arguments">time</var><a class="copiable-link" href="#index-time_002dnanosecond"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-time_002dsecond"><span class="category-def">Function: </span><span><strong class="def-name">time-second</strong> <var class="def-var-arguments">time</var><a class="copiable-link" href="#index-time_002dsecond"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-set_002dtime_002dtype_0021"><span class="category-def">Function: </span><span><strong class="def-name">set-time-type!</strong> <var class="def-var-arguments">time type</var><a class="copiable-link" href="#index-set_002dtime_002dtype_0021"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-set_002dtime_002dnanosecond_0021"><span class="category-def">Function: </span><span><strong class="def-name">set-time-nanosecond!</strong> <var class="def-var-arguments">time nsec</var><a class="copiable-link" href="#index-set_002dtime_002dnanosecond_0021"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-set_002dtime_002dsecond_0021"><span class="category-def">Function: </span><span><strong class="def-name">set-time-second!</strong> <var class="def-var-arguments">time sec</var><a class="copiable-link" href="#index-set_002dtime_002dsecond_0021"> ¶</a></span></dt>
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<dd><p>Get or set the type, seconds or nanoseconds fields of a time object.
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</p>
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<p><code class="code">set-time-type!</code> merely changes the field, it doesn’t convert the
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time value. For conversions, see <a class="ref" href="SRFI_002d19-Time_002fDate-conversions.html">SRFI-19 Time/Date conversions</a>.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-copy_002dtime"><span class="category-def">Function: </span><span><strong class="def-name">copy-time</strong> <var class="def-var-arguments">time</var><a class="copiable-link" href="#index-copy_002dtime"> ¶</a></span></dt>
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<dd><p>Return a new time object, which is a copy of the given <var class="var">time</var>.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-current_002dtime-2"><span class="category-def">Function: </span><span><strong class="def-name">current-time</strong> <var class="def-var-arguments">[type]</var><a class="copiable-link" href="#index-current_002dtime-2"> ¶</a></span></dt>
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<dd><p>Return the current time of the given <var class="var">type</var>. The default
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<var class="var">type</var> is <code class="code">time-utc</code>.
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</p>
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<p>Note that the name <code class="code">current-time</code> conflicts with the Guile core
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<code class="code">current-time</code> function (see <a class="pxref" href="Time.html">Time</a>) as well as the SRFI-18
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<code class="code">current-time</code> function (see <a class="pxref" href="SRFI_002d18-Time.html">SRFI-18 Time</a>). Applications
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wanting to use more than one of these functions will need to refer to
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them by different names.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-time_002dresolution"><span class="category-def">Function: </span><span><strong class="def-name">time-resolution</strong> <var class="def-var-arguments">[type]</var><a class="copiable-link" href="#index-time_002dresolution"> ¶</a></span></dt>
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<dd><p>Return the resolution, in nanoseconds, of the given time <var class="var">type</var>.
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The default <var class="var">type</var> is <code class="code">time-utc</code>.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-time_003c_003d_003f"><span class="category-def">Function: </span><span><strong class="def-name">time<=?</strong> <var class="def-var-arguments">t1 t2</var><a class="copiable-link" href="#index-time_003c_003d_003f"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-time_003c_003f"><span class="category-def">Function: </span><span><strong class="def-name">time<?</strong> <var class="def-var-arguments">t1 t2</var><a class="copiable-link" href="#index-time_003c_003f"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-time_003d_003f"><span class="category-def">Function: </span><span><strong class="def-name">time=?</strong> <var class="def-var-arguments">t1 t2</var><a class="copiable-link" href="#index-time_003d_003f"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-time_003e_003d_003f"><span class="category-def">Function: </span><span><strong class="def-name">time>=?</strong> <var class="def-var-arguments">t1 t2</var><a class="copiable-link" href="#index-time_003e_003d_003f"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-time_003e_003f"><span class="category-def">Function: </span><span><strong class="def-name">time>?</strong> <var class="def-var-arguments">t1 t2</var><a class="copiable-link" href="#index-time_003e_003f"> ¶</a></span></dt>
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<dd><p>Return <code class="code">#t</code> or <code class="code">#f</code> according to the respective relation
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between time objects <var class="var">t1</var> and <var class="var">t2</var>. <var class="var">t1</var> and <var class="var">t2</var>
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must be the same time type.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-time_002ddifference"><span class="category-def">Function: </span><span><strong class="def-name">time-difference</strong> <var class="def-var-arguments">t1 t2</var><a class="copiable-link" href="#index-time_002ddifference"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-time_002ddifference_0021"><span class="category-def">Function: </span><span><strong class="def-name">time-difference!</strong> <var class="def-var-arguments">t1 t2</var><a class="copiable-link" href="#index-time_002ddifference_0021"> ¶</a></span></dt>
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<dd><p>Return a time object of type <code class="code">time-duration</code> representing the
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period between <var class="var">t1</var> and <var class="var">t2</var>. <var class="var">t1</var> and <var class="var">t2</var> must be
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the same time type.
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</p>
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<p><code class="code">time-difference</code> returns a new time object,
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<code class="code">time-difference!</code> may modify <var class="var">t1</var> to form its return.
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</p></dd></dl>
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<dl class="first-deffn first-defun-alias-first-deffn">
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<dt class="deffn defun-alias-deffn" id="index-add_002dduration"><span class="category-def">Function: </span><span><strong class="def-name">add-duration</strong> <var class="def-var-arguments">time duration</var><a class="copiable-link" href="#index-add_002dduration"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-add_002dduration_0021"><span class="category-def">Function: </span><span><strong class="def-name">add-duration!</strong> <var class="def-var-arguments">time duration</var><a class="copiable-link" href="#index-add_002dduration_0021"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-subtract_002dduration"><span class="category-def">Function: </span><span><strong class="def-name">subtract-duration</strong> <var class="def-var-arguments">time duration</var><a class="copiable-link" href="#index-subtract_002dduration"> ¶</a></span></dt>
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<dt class="deffnx defunx-alias-deffnx def-cmd-deffn" id="index-subtract_002dduration_0021"><span class="category-def">Function: </span><span><strong class="def-name">subtract-duration!</strong> <var class="def-var-arguments">time duration</var><a class="copiable-link" href="#index-subtract_002dduration_0021"> ¶</a></span></dt>
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<dd><p>Return a time object which is <var class="var">time</var> with the given <var class="var">duration</var>
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added or subtracted. <var class="var">duration</var> must be a time object of type
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<code class="code">time-duration</code>.
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</p>
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<p><code class="code">add-duration</code> and <code class="code">subtract-duration</code> return a new time
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object. <code class="code">add-duration!</code> and <code class="code">subtract-duration!</code> may modify
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the given <var class="var">time</var> to form their return.
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</p></dd></dl>
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</div>
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<p>
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Next: <a href="SRFI_002d19-Date.html">SRFI-19 Date</a>, Previous: <a href="SRFI_002d19-Introduction.html">SRFI-19 Introduction</a>, Up: <a href="SRFI_002d19.html">SRFI-19 - Time/Date Library</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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