repr(::Vec) is broken

[dzhang314]

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julia> using SIMD

julia> println(repr(Vec(1.0, 2.0, 3.0, 4.0)))
<4 x Float64>[1.0, 2.0, 3.0, 4.0]

julia> <4 x Float64>[1.0, 2.0, 3.0, 4.0]
ERROR: ParseError:
# Error @ REPL[3]:1:1
<4 x Float64>[1.0, 2.0, 3.0, 4.0]
╙ ── not a unary operator
Stacktrace:
 [1] top-level scope
   @ none:1

In general, the output of repr(x) is supposed to be an executable Julia expression that evaluates to x. I just fixed the same issue in MultiFloats.jl and realized it also exists upstream in SIMD.jl.

You can see the approach I took to fix this problem in commit c996294. Basically, instead of overloading Base.show(::IO, ::MultiFloat) directly, I separately overload Base.show(::IO, ::MIME"text/plain", ::MultiFloat) and Base.print(::IO, ::MultiFloat) to print the pretty representation of a MultiFloat, which lets the default Base.show implementation print the ugly-but-executable representation. This still prints the pretty representation in functions like string and println and the Julia/IJulia REPL.

In fact, feel free to use my code for showing a Vec:

        show(io, Vec{N,T})
        write(io, "((")
        for i = 1:N
            if i > 1
                write(io, ", ")
            end
            show(io, vec[i])
        end
        write(io, "))")