A simple swap macro

output

ERROR: b not defined
 in include at boot.jl:245
 in include_from_node1 at loading.jl:128
 in process_options at client.jl:285
 in _start at client.jl:354
while loading /home/wilfred/projects/comparative_macrology/swap.jl, in expression starting on line 3

swap.jl

macro swap!(x, y)
    quote
        tmp = $y
        $x = $y
        $y = tmp
    end
end

a = 1
b = 2

# Runs fine if I comment out this line
@swap!(a, b)

println("a: $a, b: $b")