Tweak printing of Julia parent types (#1883)

So that e.g. `Integers{BigInt}` and `Integers{Int}` don't print
identically.

src/julia/Float.jl

@@ -54,10 +54,14 @@ is_positive(n::T) where T<:Real = n > zero(T)
 #
 ###############################################################################
 
-function show(io::IO, R::Floats)
+function show(io::IO, R::Floats{BigFloat})
    print(io, "Floats")
 end
 
+function show(io::IO, R::Floats{T}) where T
+   print(io, "Floats{$T}()")
+end
+
 function expressify(a::AbstractFloat; context = nothing)
    if a < 0
       return Expr(:call, :-, string(-a))

src/julia/Integer.jl

@@ -58,10 +58,14 @@ function expressify(a::Integer; context = nothing)
     return a
 end
 
-function show(io::IO, R::Integers)
+function show(io::IO, R::Integers{BigInt})
    print(io, "Integers")
 end
 
+function show(io::IO, R::Integers{T}) where T
+   print(io, "Integers{$T}()")
+end
+
 ###############################################################################
 #
 #   Modular arithmetic

src/julia/Rational.jl

@@ -70,10 +70,14 @@ function expressify(a::Rational; context = nothing)
     end
 end
 
-function show(io::IO, R::Rationals)
+function show(io::IO, R::Rationals{BigInt})
    print(io, "Rationals")
 end
 
+function show(io::IO, R::Rationals{T}) where T
+   print(io, "Rationals{$T}()")
+end
+
 ###############################################################################
 #
 #   Divides