Why does is_float(foo) not tell Vector that it can evaluate foo <= 0.23? (E100 issue)

[jerrac]

I'm experimenting with Vector and keep running into the E100 error for expressions similar to:

exists(.name) && .name == "load5" && exists(.gauge) && exists(.gauge.value) && is_float(.gauge.value) && .gauge.value >= 0.1

error[E100]: unhandled error
  ┌─ :1:106
  │
1 │ exists(.name) && .name == "load5" && exists(.gauge) && exists(.gauge.value) && is_float(.gauge.value) && .gauge.value >= 0.1
  │                                                                                                          ^^^^^^^^^^^^^^^^^^^
  │                                                                                                          │
  │                                                                                                          expression can result in runtime error
  │                                                                                                          handle the error case to ensure runtime success
  │
  = see documentation about error handling at https://errors.vrl.dev/#handling
  = learn more about error code 100 at https://errors.vrl.dev/100
  = see language documentation at https://vrl.dev
  = try your code in the VRL REPL, learn more at https://vrl.dev/examples

I understand the need to check that .gauge.value is actually a float and can be compared. What I don't get is why this expression doesn't work.

exists(.gauge) && exists(.gauge.value) makes sure it is not null, right? And is_float(.gauge.value) will be false if it isn't a float.

That should mean that, by the time it gets to .gauge.value >= 0.1, Vector should be aware that .gauge.value is a float.

So why is Vector throwing that E100 error?

Thanks in advance. :)

FYI, I'm testing by manually running the binary downloaded today on an Ubuntu 22.04 vagrant vm.

[jszwedko]

Hi @jerrac !

The issue is that the compiler isn't smart enough to realize that .gauge.value is a float at the point where that comparison is done. You'll need to wrap it in float!(.gauge.value). #91 is tracking this as an enhancement.

[jerrac]

Thanks for the answer. Hopefully that enhancement lands sometime soon. :)