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More documentation of strings and keywords

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Currently, HyKeyword is not in fact a subclass of HyString, so I removed that statement.
This commit is contained in:
Kodi Arfer 2017-03-30 12:30:00 -07:00 committed by Tuukka Turto
parent 61daf98111
commit 36d09cb194
2 changed files with 24 additions and 8 deletions
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25
docs/language/api.rst
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@ -55,8 +55,13 @@ digits.
string literals
---------------
Unlike Python, Hy allows only double-quoted strings. The single-quote character
is reserved for preventing the evaluation of a form, as in most Lisps.
Unlike Python, Hy allows only double-quoted strings (e.g., ``"hello"``). The
single-quote character ``'`` is reserved for preventing the evaluation of a
form (e.g., ``'(+ 1 1)``), as in most Lisps.
Python's so-called triple-quoted strings (e.g., ``'''hello'''`` and
``"""hello"""``) aren't supported. However, in Hy, unlike Python, any string
literal can contain newlines.
Whether running under Python 2 or Python 3, Hy treats string literals as
sequences of Unicode characters by default, and allows you to prefix a literal
@ -65,6 +70,22 @@ Hy translates ``"foo"`` and ``b"foo"`` to the identical Python code, but when
running under Python 2, ``"foo"`` is translated to ``u"foo"`` and ``b"foo"`` is
translated to ``"foo"``.
.. _syntax-keywords:
keywords
--------
An identifier headed by a colon, such as ``:foo``, is a keyword. Keywords
evaluate to a string preceded by the Unicode non-character code point U+FDD0,
like ``"\ufdd0:foo"``, so ``:foo`` and ``":foo"`` aren't equal. However, if a
literal keyword appears in a function call, it's used to indicate a keyword
argument rather than passed in as a value. For example, ``(f :foo 3)`` calls
the function ``f`` with the keyword argument named ``foo`` set to ``3``. Hence,
trying to call a function on a literal keyword may fail: ``(f :foo)`` yields
the error ``Keyword argument :foo needs a value``. To avoid this, you can quote
the keyword, as in ``(f ':foo)``, or use it as the value of another keyword
argument, as in ``(f :arg :foo)``.
Built-Ins
=========

7
docs/language/internals.rst
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@ -160,12 +160,7 @@ HyKeyword
~~~~~~~~~
``hy.models.HyKeyword`` represents keywords in Hy. Keywords are
symbols starting with a ``:``. The class inherits :ref:`HyString`.
To distinguish :ref:`HyKeywords <HyKeyword>` from :ref:`HySymbols
<HySymbol>`, without the possibility of (involuntary) clashes, the
private-use unicode character ``"\uFDD0"`` is prepended to the keyword
literal before storage.
symbols starting with a ``:``. See :ref:`syntax-keywords`.
.. _hycons: