heitml Runtime Errors

This is an example of a runtime error display:

And if you click on the file name appearing after the message "Click here to open source window", a new browser window opens and shows:

// Example for runtime error messages
This is an example of a runtime error display:
<p>

<let x = "Hello">

<let gl.x = x + "World">

<? gl.x>

<? ->y> 

The blinking red arrow shows the position where the error occurred. In this case the variable y is undefined.

The runtime error display shows all local and global variables, as well as any session variables and form input variables if they are present.

If several nested Tags have been called and the error occurred somewhere inside the nested Tag invocations, the call hierarchy shows where these tags were called from. You can click on each source link to show the corresponding source position. You can also look at the local variables of the nested tag invocations.

Additionally, heitml can show more complex tuple data structures. They are self-explaining and the reader is encouraged to try them out.

It can sometimes be useful to intentionally insert a runtime error at a position where you want to inspect the current values of your variables.