Correct parsing of chains of < and <=

Parsing a chain of comparison operators, such as 1 <= x < 10 is a quite natural thing for humans to do. However, how to best represent this doesn’t seem quite as clear cut to me. Which of the <= and < signs comes first? Or should we somehow encode that they’re at the same level? Or…?

For the record, this is what the compute-engine currently does. It’s a bit inconsistent.

[arnog]

Yes, that could work as well.

BTW, ["Less"] is a valid MathJSON expression: it’s the partial application of the Less function to no arguments (["Less", 0] is the partial application of the Less function)

[stefnotch]

I realized that Mathematica has the same problem. So clearly, it would make sense to check what they’re doing.

The following piece of code

SetAttributes[fullFormString, HoldAll];
fullFormString[expr_] := ToString[Unevaluated @ FullForm[expr]]
fullFormString[1<x<=k]

(Source: https://mathematica.stackexchange.com/a/152438 )

returns

Inequality[1, Less, x, LessEqual, k]

Which seems like a rather reasonable way of doing it in the compute engine. I guess functions would have to be wrapped in brackets or something, so that they can be distinguished from variables. ["Inequality", 1, ["Less"], "x", ["LessEqual"], "k"]

And here is their relevant documentation https://reference.wolfram.com/language/ref/FullForm.html and https://reference.wolfram.com/language/ref/TreeForm.html