Re: Incompatible types #<IntegerType int> and #<BooleanType boolean>.

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Nick Howard

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Apr 5, 2013, 4:14:03 PM4/5/13

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I think this is an issue with Mirah's error reporting. You can fix it by changing one of your usages of value to use a different name.

Looking at the AST inspection, it looks like you have something like this in your code

loop do
value = detector.readValue < 5
LCD.drawString "#{value} ", 0
end

And in the same scope, you assign 123 to value. This causes an error in type inference because the typer doesn't know whether the variable value is an int or a boolean.

The reason the message is so confusing is because Mirah's reported the drawLine error instead of the assignment error.

I added an issue for the problem (https://github.com/mirah/mirah/issues/214). Thanks for reporting it. Let us know if you have any other issues.

On Fri, Apr 5, 2013 at 11:47 AM, Peter Ehrlich <peter.i...@gmail.com> wrote:

I've got this piece of code which won't compile:

value = 123
LCD.drawInt(123, 0, 6)

LCD.drawInt(value, 0, 7)

Fails:

> mirahc --classpath /Users/peter/Downloads/leJOS_NXJ_0.9.1beta-3/lib/nxt/classes.jar main.mirah
Parsing...

main.mirah
Inferring types...
Inference Error:
main.mirah:78: Incompatible types #<IntegerType int> and #<BooleanType boolean>.
LCD.drawInt(value, 0, 6)

^^^^^

Here is the verbose output: https://gist.github.com/pehrlich/14d4bca4fd9efa00fb3f

Here is the docs on drawInt: http://lejos.sourceforge.net/p_technologies/nxt/nxj/api/lejos/nxt/LCD.html#drawInt(int, int, int)

Questions:
- ) What's this error mean? How can I fix it?
- ) Is there any way I can an internal backtrace in this error? For debugging, I was able to find the line in the Mirah gem which threw this error, but not what called that method. --trace and --backtrace aren't recognized

Thanks!!!
--Peter

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