const vs. func

[zilinc]

foo : U32
foo = let x = bar 1
       in x + 3

bar : U32 -> U32

is accepted by the compiler, whereas foo is not necessarily a constant.

poly : all a. a
poly = poly' ()

poly' : all a. () -> a

fails to parse (because const can't have a poklytype) so cannot be made a constant.

Do we still have a reason to differentiate functions and constants? Will the code generator or verification toolchain do something bad with the first code snippet?