Confusing error when adding too many type parameters

[jakobnissen]

The following error message is quite confusing:

julia> BitVector{1}
ERROR: TypeError: in Type{...} expression, expected UnionAll, got Type{BitVector}
Stacktrace:
 [1] top-level scope
   @ REPL[5]:1

The problem with the code is that BitVector does not take any type parameters. In contrast, if you make the same error with BitArray, which does take type parameters, you get a much nicer error:

julia> BitArray{1,2}
ERROR: too many parameters for type
Stacktrace:
 [1] top-level scope
   @ REPL[8]:1

I think it would be nicer if:

• The former error instead said something like: "Type BitVector takes no parameters, got 1"
• The latter error also mentioned which type got too many parameters: "too many parameters for type BitArray"

[Seelengrab]

It's a bit different - BitVector{1} is actually this:

julia> BitArray{1}{1}
ERROR: TypeError: in Type{...} expression, expected UnionAll, got Type{BitVector}
Stacktrace:
 [1] top-level scope
   @ REPL[2]:1

It's just not exposed that BitVector is actually an BitArray{1} here..