Julia answer to text benchmarks (http://matthewrocklin.com/blog/work/2014/01/13/Text-Benchmarks/)

juliabench.jl

function groupby{T}(fn::Function, seq::Array{T})
    dict = Dict{Any, Array{T}}();
    for item in seq
        key = fn(item);
        if !haskey(dict, key)
            dict[key] = [];
        end
        push!(dict[key], item);
    end
    return dict;
end

function processdata(file::String)
    filename = ARGS[1];
    file = open(filename);
    lines = readlines(file);
    #lines = convert(Array{String, 1}, map(strip, lines));
    lines = map(strip, lines)
    word_pairs = map(s->split(s, ','), lines);
    result = groupby(a->a[1], word_pairs);
end

processdata("test.txt")

@time begin
    result = processdata(ARGS[1]);
end 

test.txt

it, was
was, the