Evaluating does not work as expected if the resulting is floating-point and given parameters are un/signed-integers

[Dentrax]

Hey there, I was playing with this awesome expression library awhile! But I hit a bug that ended-up do me to debugging my app for a few hours. And noticed it was due to my expression which blocking my progress on my project currently. I also search for whether this is a known issue or not, but couldn't find much. Here is a minimal reproducible snippet:

package main

import (
	"fmt"
	"github.com/antonmedv/expr"
)

func main() {
	env := map[string]uint64{
		"foo":  3,
		"bar":  5,
	}

	code := `(foo / bar) < 0.5`

	program, err := expr.Compile(code, expr.Env(env))
	if err != nil {
		panic(err)
	}

	output, err := expr.Run(program, env)
	if err != nil {
		panic(err)
	}

	fmt.Println(output)
}

Bug

Given foo is 3 and bar is 5, resulting 0 if we evaluate with (foo / bar) expression. But actually it should return 0.6 instead. So eventually my (foo / bar) < 0.5 expression also return false instead of true. It's evaluating as true because of 0 < 0.5 is "true".

I'm not so sure if it's correct by design, since int/int resulting int in Go. So that expr resulting 0 as expected. But from the end-user perspective, I was expecting it should have floating-point value. (at least this is what most modern calculators' do, given 3/5 is just 0.6.)

• Tested with the following primitive types: byte, int8, int16, int32, int64, uint8, uint16, uint32, uint64
• Works only if all the given parameters are: float32 and float64

[antonmedv]

This is nice point. I think we can change resulting type for / op to float64.

[Dentrax]

This is nice point. I think we can change resulting type for / op to float64.

Cool! What about other operators? I think all operators should result float64. 🤔 (i.e. 1.5 + 9.3333, 9 - 8.9, 0.0003 * 2.33, didn't test, just for an example.)