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Nicer English (#5513)

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mark-summerfield
2017-03-12 18:55:14 +00:00
committed by Andreas Rumpf
parent 974b4d59b4
commit ef59b1a8eb
1 changed files with 9 additions and 9 deletions
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doc/tut1.rst
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@@ -1063,10 +1063,10 @@ Enumeration and object types may only be defined within a
Enumerations
------------
A variable of an enumeration type can only be assigned a value of a
limited set. This set consists of ordered symbols. Each symbol is mapped
A variable of an enumeration type can only be assigned one of the enumeration's specified values.
These values are a set of ordered symbols. Each symbol is mapped
to an integer value internally. The first symbol is represented
at runtime by 0, the second by 1 and so on. Example:
at runtime by 0, the second by 1 and so on. For example:
.. code-block:: nim
@@ -1077,17 +1077,17 @@ at runtime by 0, the second by 1 and so on. Example:
var x = south # `x` is of type `Direction`; its value is `south`
echo x # writes "south" to `stdout`
All comparison operators can be used with enumeration types.
All the comparison operators can be used with enumeration types.
An enumeration's symbol can be qualified to avoid ambiguities:
``Direction.south``.
The ``$`` operator can convert any enumeration value to its name, the ``ord``
proc to its underlying integer value.
The ``$`` operator can convert any enumeration value to its name, and the ``ord``
proc can convert it to its underlying integer value.
For better interfacing to other programming languages, the symbols of enum
types can be assigned an explicit ordinal value. However, the ordinal values
have to be in ascending order. A symbol whose ordinal value is not
must be in ascending order. A symbol whose ordinal value is not
explicitly given is assigned the value of the previous symbol + 1.
An explicit ordered enum can have *holes*:
@@ -1142,8 +1142,8 @@ subrange types (and vice versa) are allowed.
The ``system`` module defines the important `Natural <system.html#Natural>`_
type as ``range[0..high(int)]`` (`high <system.html#high>`_ returns the
maximal value). Other programming languages mandate the usage of unsigned
integers for natural numbers. This is often **wrong**: you don't want unsigned
maximal value). Other programming languages may suggest the use of unsigned
integers for natural numbers. This is often **unwise**: you don't want unsigned
arithmetic (which wraps around) just because the numbers cannot be negative.
Nim's ``Natural`` type helps to avoid this common programming error.