View source for Talk:Display an outline as a nested table

===Why display an outline as a table ?===

The current Perl6 draft expresses some helpful puzzlement about this :-) 

The answer is that there are two quite different modes of outline – topic nests and propositional nests.
# Sub-'''topics''' nested inside the topics which they ''sub-divide'' – the classic serially-labelled TOC pattern which the Perl 6 entry is showing.
# Supporting '''points''' nested under the key points which they ''support or clarify''.


(And it may well be that the task example could helpfully be replaced by a clearer example of the latter)

When the outline expresses propositional hierarchies (rather than sub-divisions of domains), indented lines ('outlines') have two disadvantages:

# Logically connected peers are visually driven further and further apart as subordinate elaboration expands, and cognitive work is required to reconnect the 'sentences' which they form when read together.
# The 'vertical' metaphor of '''support''' (evidence supporting claim, example supporting clarity etc etc) is replaced by a visually less direct horizontal convention, and, again, takes some cognitive work to reconstruct.


A potential *weakness* of tabular representations of argument/exposition structures is, of course, that some horizontal contiguities are more meaningful than others.  One solution is to add more space at the margins where the edges of sub-trees meet, and another is to distinguish adjacent subtrees by color – hence the '''extra credit''' task of using color to reveal the borders between sub-trees.

In short, tabular representation can be very useful in: 

# the visual presentation of nested key points and supporting points (rather than sub-divided topics)
# and the teaching of argument structure.


(The current Perl6 color scheme rather helpfully shows that I failed to make this at all obvious or clear :-) Thank you ! [[User:Hout|Hout]] ([[User talk:Hout|talk]]) 04:36, 24 October 2019 (UTC)

===When an outline is more a forest than a tree===

The test sample here is an outline with only one top level root node – we can think of it as representing a single tree.

In practice, of course, an indented text outline will often have several top level (unindented) lines.
To put it another way, many outlines represent forests – lists of trees – rather than single trees (or can otherwise be thought of as a single tree with a hidden virtual root).

FWIW I've updated the Haskell, JavaScript and Functional Python versions here to allow for the forest case by writing out a series of (wiki) tables, one for each tree, separated by a couple of linefeeds.
[[User:Hout|Hout]] ([[User talk:Hout|talk]]) 15:19, 6 September 2021 (UTC)

For example, a forest outline – with several top-level nodes – like:
<pre>alpha
    beta
    gamma
delta
    epsilon
    zeta
eta
    theta
    iota</pre>

might be rendered by the following sequence of space-separated tree-tables:
{| class="wikitable" style="text-align: center;"
|-
| style="background: #ffffe6; " colspan=2 | alpha
|-
| style="background: #ffebd2; " | beta
| style="background: #f0fff0; " | gamma
|}

{| class="wikitable" style="text-align: center;"
|-
| style="background: #ffffe6; " colspan=2 | delta
|-
| style="background: #ffebd2; " | epsilon
| style="background: #f0fff0; " | zeta
|}

{| class="wikitable" style="text-align: center;"
|-
| style="background: #ffffe6; " colspan=2 | eta
|-
| style="background: #ffebd2; " | theta
| style="background: #f0fff0; " | iota
|}
[[User:Hout|Hout]] ([[User talk:Hout|talk]]) 15:41, 6 September 2021 (UTC)

where the following (single root / tree):

<pre>top level
    alpha
        beta
        gamma
    delta
        epsilon
        zeta
    eta
        theta
        iota</pre>

would have rendered as:
{| class="wikitable" style="text-align: center;"
|-
| style="background: #ffffe6; " colspan=6 | top level
|-
| style="background: #ffebd2; " colspan=2 | alpha
| style="background: #f0fff0; " colspan=2 | delta
| style="background: #e6ffff; " colspan=2 | eta
|-
| style="background: #ffebd2; " | beta
| style="background: #ffebd2; " | gamma
| style="background: #f0fff0; " | epsilon
| style="background: #f0fff0; " | zeta
| style="background: #e6ffff; " | theta
| style="background: #e6ffff; " | iota
|}
[[User:Hout|Hout]] ([[User talk:Hout|talk]]) 15:49, 6 September 2021 (UTC)