A bad implementation of Soundex in Julia. Not sure if its working though

soundex.jl

function soundex(s::String)
    const head = lowercase(s[1])
    const tail = lowercase(s[2:end])

    const dict= [ "a"=>"", "e"=>"", "i"=>"", "o"=>"", "u"=>"", "y"=>"", "h"=>"", "w"=>"", "b"=>"1", "f"=>"1", "p"=>"1", "v"=>"1", "c"=>"2", "g"=>"2", "j"=>"2", "k"=>"2", "q"=>"2", "s"=>"2", "x"=>"2", "z"=>"2", "d"=>"3", "t"=>"3", "l"=>"4", "m"=>"5", "n"=>"5", "r"=>"6"]

    const t=split(tail,"")
    const t1=map(x->dict[x],t)

    output=ASCIIString[]
    prev=""
    index=0
    for c in t1
      if c!=prev
        prev=c
        append!(output,[c])
      end
      index+=1
    end

    return string( uppercase(head),join(output), "0000")[1:4]
end