In addition to this static demo, I also have a live demo here.

The program is:

## Statistical functions

\list_mean=(\xs / (list_sum xs) (list_length xs))

\list_variance=
    (\list
    \mean=(list_mean list)
    \diff=(map (\val - val mean) list)
    \square_diff=(map (\val * val val) diff)
    list_mean square_diff
    )

\list_stddev=(\list sqrt; list_variance list)

## Output functions

\p=(say "<p>")
\pre=(tag "pre")

\show=
    (\label\val
    put [label " = "]
    is_list val
        (each val \x put [x " "])
        (put val)
    nl
    )

## (show_stats list) Shows the statistics for the given list.
\show_stats=
    (\list
    tag "h2" (say "Show Stats")
    p
    say "First call the list_stddev function directly to get the final answer."

    pre
    (
    show "list" list
    \stddev=(list_stddev list)
    show "stddev" stddev
    )

    p
    say "Now show how we arrive at that answer."

    pre
    (
    \sum=(list_sum list)
    \count=(list_length list)
    \mean=(list_mean list)

    show "list" list
    show "sum" sum
    show "count" count
    show "mean" mean

    \diff=(map (\val - val mean) list)
    \square_diff=(map (\val * val val) diff)

    show "diff" diff
    show "square_diff" square_diff

    \variance=(list_mean square_diff)
    show "variance" variance

    \stddev=(sqrt variance)
    show "stddev" stddev
    )
    )

# Now show the stats for a couple of lists.

show_stats [2 4 4 4 5 5 7 9]
show_stats [-11 0 6]

The output is:

Show Stats

First call the list_stddev function directly to get the final answer.
list = 2 4 4 4 5 5 7 9 
stddev = 2
Now show how we arrive at that answer.
list = 2 4 4 4 5 5 7 9 
sum = 40
count = 8
mean = 5
diff = -3 -1 -1 -1 0 0 2 4 
square_diff = 9 1 1 1 0 0 4 16 
variance = 4
stddev = 2

Show Stats

First call the list_stddev function directly to get the final answer.
list = -11 0 6 
stddev = 7.03957069398096
Now show how we arrive at that answer.
list = -11 0 6 
sum = -5
count = 3
mean = -1.66666666666667
diff = -9.33333333333333 1.66666666666667 7.66666666666667 
square_diff = 87.1111111111111 2.77777777777778 58.7777777777778 
variance = 49.5555555555556
stddev = 7.03957069398096