Reproducible.jl

using Random

const seed = hash(time())

Random.seed!(seed)

searchstring = "const seed = "
open("$(@__FILE__)" * ".reproducible", "w") do io
  for line in readlines(open(@__FILE__))
    if length(line) > length(searchstring) && line[1:length(searchstring)] == searchstring
      write(io, searchstring * "$seed\n")
    else
      write(io, line * "\n")
    end
  end
end

@show seed
@show rand()

The below as Rerunnable.jl

module Rerunnable

function rerunnable(filename, replacements)
  open(filename * ".rerunnable", "w") do io
    for line in readlines(open(filename))
      for (original, replacement) in replacements
         occursin(original, line) && (line = replace(line, original => replacement))
      end
      write(io, line * "\n")
    end
  end
end

end

and then ReproduceExample.jl

using Random
include("Rerunnable.jl") # or using when/if a package
using .Rerunnable

const seed = hash(time())

Rerunnable.rerunnable(@__FILE__,  Dict("hash(time())" => "$seed"))

Random.seed!(seed)

@show seed
@show rand()

then:

$julia ReproduceExample.jl 
seed = 0x0b8683917c9ce6a1
rand() = 0.9296335898922403

$julia ReproduceExample.jl.rerunnable 
seed = 830495842180589217
rand() = 0.9296335898922403

And ReproduceExample.jl.rerunnable is identical to ReproduceExample.jl.rerunnable.rerunnable