Runtime evaluation: Difference between revisions

=={{header|Wren}}==

Firstly, Wren has a REPL which is started from the command line by running Wren-cli without any parameters.

Any valid Wren code can then be entered and immediately evaluated.

To quit the REPL just type Ctrl-C or Ctrl-D.

The examples in the Kotlin entry would look like this in the Wren REPL:

<pre>

$ wren-cli

\\/"-

\_/ wren v0.3.0

> 20 + 22

42

> 5 * 81.sqrt

45

> var triple = Fn.new { |x| x * 3 }

> triple.call(16)

48

>

</pre>

Secondly, Wren has the ''Meta.eval'' method which can be used from within a script to execute any valid Wren code (presented to it in string form) at runtime. The string could be constructed within the script, obtained from a file or input by the user. Here's a very simple example:

<lang ecmascript>import "meta" for Meta

var s = "for (i in 0..4) System.print(i)"

Meta.eval(s)</lang>

{{out}}

<pre>

0

1

2

3

4

</pre>