support for discrete distributions with Inf in their support gives InexactError error

[mattiasvillani]

Example:
support(Poisson(1)) # gives ERROR: InexactError: trunc(Int64, Inf)

The issue is with the line

support(d::Union{D,Type{D}}) where {D<:DiscreteUnivariateDistribution} = round(Int, minimum(d)):round(Int, maximum(d))

since maximum(Poisson(1)) returns Inf, and round(Int, Inf) gives an InexactError.

One solution is to drop the rounding in the above line, but then the support of a discrete distribution is a RealInterval, which is not great. The root problem is probably that there is no Inf of integer type in Julia.

[devmotion]

Related: JuliaLang/julia#15562

I think the correct solution would be to use https://github.com/JuliaArrays/InfiniteArrays.jl (or something similar) to represent the support of Poisson.

It seems similarly https://github.com/JuliaMath/IntervalSets.jl and https://github.com/JuliaApproximation/DomainSets.jl could be used to represent the support of continuous distributions (also multivariate ones!) more naturally.