Here is a fun and possibly useful solution (that works only on 0.4 due to call overloading):
https://gist.github.com/dpsanders/d8ef239ec8c78c4debee It introduces a `MultidimFunction` type, and a macro `@multidim` that works as follows: julia> @multidim f(x) = [sqrt(x[1]), 2x[2]] MultidimFunction([(anonymous function),(anonymous function)]) julia> f([1., 2.]) 2-element Array{Float64,1}: 1.0 4.0 julia> x = [1., 2.] 2-element Array{Float64,1}: 1.0 2.0 julia> f(x) 2-element Array{Float64,1}: 1.0 4.0 julia> f[1](x) 1.0 julia> f[2](x) 4.0 julia> y = [-1., 2.] 2-element Array{Float64,1}: -1.0 2.0 julia> f[1](y) ERROR: DomainError: sqrt will only return a complex result if called with a complex argument. try sqrt (complex(x)) in sqrt at ./math.jl:144 in anonymous at /Users/dsanders/.julia/v0.3/ValidatedNumerics/src/multidim/multidim_functions.jl:49 julia> f[2](y) 4.0 David.
