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176 lines
11 KiB
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<!-- This manual documents Guile version 3.0.10.
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Copyright (C) 1996-1997, 2000-2005, 2009-2023 Free Software Foundation,
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Inc.
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Copyright (C) 2021 Maxime Devos
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Copyright (C) 2024 Tomas Volf
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
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copy of the license is included in the section entitled "GNU Free
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Documentation License." -->
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<title>SRFI-19 Date (Guile Reference Manual)</title>
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<meta name="description" content="SRFI-19 Date (Guile Reference Manual)">
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<meta name="keywords" content="SRFI-19 Date (Guile Reference Manual)">
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<link href="Concept-Index.html" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="SRFI_002d19.html" rel="up" title="SRFI-19">
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<link href="SRFI_002d19-Time_002fDate-conversions.html" rel="next" title="SRFI-19 Time/Date conversions">
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<link href="SRFI_002d19-Time.html" rel="prev" title="SRFI-19 Time">
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</head>
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<body lang="en">
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<div class="subsubsection-level-extent" id="SRFI_002d19-Date">
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<div class="nav-panel">
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<p>
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Next: <a href="SRFI_002d19-Time_002fDate-conversions.html" accesskey="n" rel="next">SRFI-19 Time/Date conversions</a>, Previous: <a href="SRFI_002d19-Time.html" accesskey="p" rel="prev">SRFI-19 Time</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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</div>
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<hr>
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<h4 class="subsubsection" id="SRFI_002d19-Date-1"><span>7.5.16.3 SRFI-19 Date<a class="copiable-link" href="#SRFI_002d19-Date-1"> ¶</a></span></h4>
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<a class="index-entry-id" id="index-date-1"></a>
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<p>A <em class="dfn">date</em> object represents a date in the Gregorian calendar and a
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time of day on that date in some timezone.
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</p>
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<p>The fields are year, month, day, hour, minute, second, nanoseconds and
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timezone. A date object is immutable, its fields can be read but they
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cannot be modified once the object is created.
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</p>
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<p>Historically, the Gregorian calendar was only used from the latter part
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of the year 1582 onwards, and not until even later in many countries.
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Prior to that most countries used the Julian calendar. SRFI-19 does
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not deal with the Julian calendar at all, and so does not reflect this
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historical calendar reform. Instead it projects the Gregorian calendar
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back proleptically as far as necessary. When dealing with historical
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data, especially prior to the British Empire’s adoption of the Gregorian
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calendar in 1752, one should be mindful of which calendar is used in
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each context, and apply non-SRFI-19 facilities to convert where necessary.
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</p>
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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-date_003f"><span class="category-def">Function: </span><span><strong class="def-name">date?</strong> <var class="def-var-arguments">obj</var><a class="copiable-link" href="#index-date_003f"> ¶</a></span></dt>
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<dd><p>Return <code class="code">#t</code> if <var class="var">obj</var> is a date 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_002ddate"><span class="category-def">Function: </span><span><strong class="def-name">make-date</strong> <var class="def-var-arguments">nsecs seconds minutes hours date month year zone-offset</var><a class="copiable-link" href="#index-make_002ddate"> ¶</a></span></dt>
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<dd><p>Create a new date object.
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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-date_002dnanosecond"><span class="category-def">Function: </span><span><strong class="def-name">date-nanosecond</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dnanosecond"> ¶</a></span></dt>
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<dd><p>Nanoseconds, 0 to 999999999.
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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-date_002dsecond"><span class="category-def">Function: </span><span><strong class="def-name">date-second</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dsecond"> ¶</a></span></dt>
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<dd><p>Seconds, 0 to 59, or 60 for a leap second. 60 is never seen when working
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entirely within UTC, it’s only when converting to or from TAI.
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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-date_002dminute"><span class="category-def">Function: </span><span><strong class="def-name">date-minute</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dminute"> ¶</a></span></dt>
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<dd><p>Minutes, 0 to 59.
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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-date_002dhour"><span class="category-def">Function: </span><span><strong class="def-name">date-hour</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dhour"> ¶</a></span></dt>
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<dd><p>Hour, 0 to 23.
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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-date_002dday"><span class="category-def">Function: </span><span><strong class="def-name">date-day</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dday"> ¶</a></span></dt>
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<dd><p>Day of the month, 1 to 31 (or less, according to the month).
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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-date_002dmonth"><span class="category-def">Function: </span><span><strong class="def-name">date-month</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dmonth"> ¶</a></span></dt>
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<dd><p>Month, 1 to 12.
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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-date_002dyear"><span class="category-def">Function: </span><span><strong class="def-name">date-year</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dyear"> ¶</a></span></dt>
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<dd><p>Year, eg. 2003. Dates B.C. are negative, eg. <em class="math">-46</em> is 46
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B.C. There is no year 0, year <em class="math">-1</em> is followed by year 1.
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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-date_002dzone_002doffset"><span class="category-def">Function: </span><span><strong class="def-name">date-zone-offset</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dzone_002doffset"> ¶</a></span></dt>
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<dd><p>Time zone, an integer number of seconds east of Greenwich.
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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-date_002dyear_002dday"><span class="category-def">Function: </span><span><strong class="def-name">date-year-day</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dyear_002dday"> ¶</a></span></dt>
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<dd><p>Day of the year, starting from 1 for 1st January.
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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-date_002dweek_002dday"><span class="category-def">Function: </span><span><strong class="def-name">date-week-day</strong> <var class="def-var-arguments">date</var><a class="copiable-link" href="#index-date_002dweek_002dday"> ¶</a></span></dt>
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<dd><p>Day of the week, starting from 0 for Sunday.
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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-date_002dweek_002dnumber"><span class="category-def">Function: </span><span><strong class="def-name">date-week-number</strong> <var class="def-var-arguments">date dstartw</var><a class="copiable-link" href="#index-date_002dweek_002dnumber"> ¶</a></span></dt>
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<dd><p>Week of the year, ignoring a first partial week. <var class="var">dstartw</var> is the
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day of the week which is taken to start a week, 0 for Sunday, 1 for
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Monday, etc.
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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_002ddate"><span class="category-def">Function: </span><span><strong class="def-name">current-date</strong> <var class="def-var-arguments">[tz-offset]</var><a class="copiable-link" href="#index-current_002ddate"> ¶</a></span></dt>
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<dd><p>Return a date object representing the current date/time, in UTC offset
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by <var class="var">tz-offset</var>. <var class="var">tz-offset</var> is seconds east of Greenwich and
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defaults to the local timezone.
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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_002djulian_002dday"><span class="category-def">Function: </span><span><strong class="def-name">current-julian-day</strong><a class="copiable-link" href="#index-current_002djulian_002dday"> ¶</a></span></dt>
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<dd><a class="index-entry-id" id="index-julian-day-1"></a>
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<p>Return the current Julian Day.
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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_002dmodified_002djulian_002dday"><span class="category-def">Function: </span><span><strong class="def-name">current-modified-julian-day</strong><a class="copiable-link" href="#index-current_002dmodified_002djulian_002dday"> ¶</a></span></dt>
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<dd><a class="index-entry-id" id="index-modified-julian-day-1"></a>
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<p>Return the current Modified Julian Day.
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</p></dd></dl>
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</div>
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<hr>
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<div class="nav-panel">
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<p>
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Next: <a href="SRFI_002d19-Time_002fDate-conversions.html">SRFI-19 Time/Date conversions</a>, Previous: <a href="SRFI_002d19-Time.html">SRFI-19 Time</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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</div>
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