Transformation from float to bigint

[remitbri]

At the moment

let i = 1
let f = 1.3

let bigI = BigInt.fromInt(i)
let bigF = BigInt.fromFloat(f)

is compiled to

var bigI = BigInt(1);

var bigF = BigInt(1.3);

var i = 1;

var f = 1.3;

Problem: in JS, BigInt(x) is valid only if x is an integer, not a float, so running var bigF = BigInt(1.3) throws an error

[remitbri]

Potential fix:
redefining in Core__BigInt.res to

let fromFloat = t => t->Core__Int.fromFloat->fromInt

with some documentation in the interface file, maybe adapting what's already available for Core__Int.fromFloat

[bloodyowl]

@remitbri issue there is that it accepts values above the maximum safe int32 provided they don't have any decimals, not much we can do on the type level

[remitbri]

Er, not sure I'm following you about the type level. This is a compiling-to-js issue

[bloodyowl]

@remitbri BigInt(Number.MAX_VALUE) is valid even though MAX_VALUE is a float. the issue is passing a float with decimals. I propose changing the signature to #7419 to make the function return an option rather than throwing.

@cometkim does that sound good to you?