Idiomatically determine all the characters that can be used for symbols: Difference between revisions

=={{header|Nim}}==

As regards identifiers, there exists a general rule which describes how they can be formed. For this rule, the following program prints the allowed starting characters and the allowed characters:

<lang Nim>import sequtils, strutils

echo "Allowed starting characters for identifiers:"

echo toSeq(IdentStartChars).join()

echo ""

echo "Allowed characters in identifiers:"

echo toSeq(IdentChars).join()</lang>

{{out}}

<pre>Allowed starting characters for identifiers:

ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz

Allowed characters in identifiers:

0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz</pre>

But Nim is a lot more flexible and allows using Unicode symbols in identifiers provided these are letters and digits. Thus, the following program is valid:

<lang Nim>var à⁷ = 3

echo à⁷</lang>

Using escape character <code>`</code>, it is possible to override the rules and to include any character in an identifier and even to use a keyword as identifier. Here is an example of the possibilities:

<lang Nim>var `const`= 3

echo `const`

proc `<`(a, b: int): bool =

echo a, " ", b

system.`<`(a, b)

echo 4 < 7

proc `Π`(a: varargs[int]): int =

result = 1

for n in a: result *= n

echo Π(4, 5, 7)

var `1` = 2

echo `1`

</lang>