How to fix this align environment a bit neater? - latex

Question

I'm writing a description of how recursive functions are applied within lists using the align environment from amsmath in LaTeX. Here's the code:
\begin{align*}
& \reduce (+, 0, & [1, 2, 3, 4]) \\
= & \reduce (+, 0 + 1, & [2, 3, 4]) \\
= & \reduce (+, 0 + 1 + 2, & [3, 4]) \\
= & \reduce (+, 0 + 1 + 2 + 3, & [4]) \\
= & \reduce (+, 0 + 1 + 2 + 3 + 4, & []) \\
= & 0 + 1 + 2 + 3 + 4\\
= & 10
\end{align*}
or my try out to enhance the readability. Inserted \quads there:
\begin{align*}
& \reduce (+,\quad 0, & [1, 2, 3, 4]) \\
=& \reduce (+,\quad 0 + 1, & [2, 3, 4]) \\
=& \reduce (+,\quad 0 + 1 + 2, & [3, 4]) \\
=& \reduce (+,\quad 0 + 1 + 2 + 3, & [4]) \\
=& \reduce (+,\quad 0 + 1 + 2 + 3 + 4, & []) \\
=& 0 + 1 + 2 + 3 + 4\\
=& 10
\end{align*}
It just doesn't look nice. Here's a quick picture of the latter:
http://havu.viuhka.fi/kuvat/alignenv.png
It is almost both readable and aesthetical, but not quite.
How to make the gap smaller? And any other tips you may have are appreciated!

Answer 1

How about using a tabular environment instead of align, with which you can more easily control alignment of the columns? I personally liked the results of:
\begin{tabular}{ r l c }
& reduce(+,\;\, 0, & [1, 2, 3, 4]) \\
=& reduce(+,\;\, 0 + 1, & [2, 3, 4]) \\
=& reduce(+,\;\, 0 + 1 + 2, & [3, 4]) \\
=& reduce(+,\;\, 0 + 1 + 2 + 3, & [4]) \\
=& reduce(+,\;\, 0 + 1 + 2 + 3 + 4, & []) \\
=& 0 + 1 + 2 + 3 + 4\\
=& 10
\end{tabular}
Causes the set on the right to form (visually speaking) an upside down triangle shape. I also replaced \quad with \;\, \quad seemed like too much, and \; not enough... space there.
I briefly considered doing the same to the sums in their own column, but decided that the sums 'growing to the right' was visually more effective.