Broadcast AbstractRNG like a scalar

Author: nickrobinson251

NEWS.md

@@ -41,11 +41,13 @@ Standard library changes
 
 * `dot` now admits a 3-argument method `dot(x, A, y)` to compute generalized dot products `dot(x, A*y)`, but without computing and storing the intermediate result `A*y` ([#32739]).
 
-#### SparseArrays
+#### Random
 
+* `AbstractRNG`s now behave like scalars when used in broadcasting ([]).
 
-#### Dates
+#### SparseArrays
 
+#### Dates
 
 #### Statistics
 

stdlib/Random/src/Random.jl

@@ -40,6 +40,8 @@ Supertype for random number generators such as [`MersenneTwister`](@ref) and [`R
 """
 abstract type AbstractRNG end
 
+Base.broadcastable(x::AbstractRNG) = Ref(x)
+
 gentype(::Type{X}) where {X} = eltype(X)
 gentype(x) = gentype(typeof(x))
 

stdlib/Random/test/runtests.jl

@@ -774,3 +774,7 @@ end
     @test Sampler(GLOBAL_RNG, 2:4, Val(1)) isa SamplerRangeFast
     @test Sampler(GLOBAL_RNG, 2:4, Val(Inf)) isa SamplerRangeFast
 end
+
+@testset "RNGs broadcast as scalars: T" for T in (MersenneTwister, RandomDevice)
+    @test length.(rand.(T(), 1:3) == 1:3
+end