[BUG] Function composition crash

[afarnham]

Bug Description

Function composition crashes with error: Execution was interrupted, reason: signal SIGSEGV: invalid address (fault address: 0x0). The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.

I would expect to be able to call the composed function.

Steps to Reproduce

1. Paste the following a cell

fn square(x: Int) -> Int:
    return x * x

fn incr(x: Int) -> Int:
    return x + 1

fn compose[A: AnyType, B: AnyType, C: AnyType](f: fn(A) -> B, g: fn(B) -> C) -> fn(A) capturing -> C:
    fn bar(a: A) -> C:
        return g(f(a))
    return bar

let incrsq = compose[Int, Int, Int](incr, square)
let v = incrsq(2)
print(v)

3. Run the cell.

Context

11:devices:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
10:freezer:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
9:cpuset:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
8:pids:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
7:perf_event:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
6:cpu,cpuacct:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
5:memory:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
4:net_cls,net_prio:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
3:hugetlb:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
2:blkio:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
1:name=systemd:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod326bc94d_94c0_4508_bb3f_3cac351d8df0.slice/cri-containerd-a4e2b628060ae6451b74a121c757bf18ea73e5ad7a7ea262da1cd5a43f52dd24.scope
0::/

[Mogball]

This is because the closure state is stack-allocated (which is not desirable). Closing in favour of #217