Silent type promotion when creating range using `a🅱c`

General Usage
2

What’s happening is more explicit with Float64:

julia> typeof(0:0.1:1)
StepRangeLen{Float64, Base.TwicePrecision{Float64}, Base.TwicePrecision{Float64}, Int64}

It’s a design choice, and certainly a debatable one at that. It’s done to avoid roundoff issues. Compare

julia> collect(0:0.1:1)
11-element Vector{Float64}:
 0.0
 0.1
 0.2
 0.3
 0.4
 0.5
 0.6
 0.7
 0.8
 0.9
 1.0

julia> collect(StepRangeLen(0,0.1,11))
11-element Vector{Float64}:
 0.0
 0.1
 0.2
 0.30000000000000004
 0.4
 0.5
 0.6000000000000001
 0.7000000000000001
 0.8
 0.9
 1.0

This issue appears cosmetic, but it can actually lead to significant ambiguity. Knowing that 0.1*3 == 0.30000000000000004 > 0.3, should last(0.0:0.1:0.3) be 2.0, 3.0, or 0.30000000000000004? The TwicePrecision step is the only way to give the user what they (usually) want while maintaining consistency.

But I will sympathize that I, too, find it a tedious to have to use the StepRangeLen constructor when I’m okay with a lower precision step. Especially because there is a performance cost.