Isolating part of a student's input

I’m asking students to type inequalities of the form

a\le x\le b

into a column of a table. I’d like to isolate the numbers a and b that the students type for use inside of CL. In other words, I’d like to be able to define a number in CL script that equals whatever students type in for a, and another number for b. I guess I will also need a warning message when students type something that doesn’t match the intended form.

In the “Types” section of the CL documentation there is a lot of stuff about patterns and matching which may be relevant here, but there is no code sample so I’m not quite sure how to use these features.

Great question - it’s something we’re aware of the need for, and working to make available, but that’s not a public feature yet.

Any progress on this? I am in need of the same thing in order to build an animated number line diagram where the student enters an expression, like 2+3, and the graph animates a number line diagram. I’ve got it built except for pulling out the “2” and the “3” from the math input.