Example which doesn't work in v4.x

[kushti]

UPD[@aslesarenko]:
Make sure the following example works with JITC.

For example,

path.fold(item, {(a: (Coll[Byte], Coll[Byte])) =>
a._1.zip(a._2).map({ (c: (Byte, Byte)) => (c._1 ^ c._2).toByte })
})

does not compile, and I'm not sure whether it is okay or not. Please describe fold limitations in the spec.

[aslesarenko]

@kushti is this example is committed to some branch to reproduce?

[aslesarenko]

Nested loops are not supported in in AOT costing.
Here map is nested in Fold and hence leads to error.
This example should work fine with JIT costing, moving to 4.0 milestone.

[aslesarenko]

bitwise xor operation ^ is not implemented in v4.x and in v5.0.
So, exactly that example will not work in v5.0, but the following will work

val foo = path.fold(item, { (a: Coll[Byte], b: Coll[Byte]) =>
    a.zip(b).map({ (c: (Byte, Byte)) => (c._1 + c._2).toByte })
  })

See property("nested loops: map inside fold")

[aslesarenko]

Implementing ^ is part of #474 and will be done there. The test for this example is added, this issue can be closed.