Integer division doesn't work with left operands larger than LONG_MAX

[Mischa-Alff]

The issue at elm-compiler#878 mentions it, but it's in the wrong repo, so I'm recreating it here.

LHS arguments greater than LONG_MAX(4294967295) return a negative number when using integer division (//).

main = asText (4294967295 // 2)
-- shows 2147483647

main = asText (4294967296 // 2)
-- shows -2147483648

This is because elm-core's src/Native/Basics.js div function is a/b|0, thus using JavaScript's OR operator, which most converts the LHS to a 32-bit integer and returns a 32-bit integer.

EDIT: I read the JS spec, it's not a bug with JS, just another one of its problems.

[int-index]

I have encountered this bug and my workaround was to define my own integer division:

(//) : Int -> Int -> Int
a // b = floor (Basics.toFloat a / Basics.toFloat b)

Is there a better implementation?

[int-index]

I have encountered this bug and my workaround was to define my own integer division:

(//) : Int -> Int -> Int
a // b = floor (Basics.toFloat a / Basics.toFloat b)

Is there a better implementation?

[evancz]

Consolidated all the math related stuff into the #721 meta issue. Follow along there!

[evancz]

Consolidated all the math related stuff into the #721 meta issue. Follow along there!