[Inquiry] Re: Theme One Program -- Commentary

[Jon Awbrey]

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TOP.  Commentary Note 7

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Upon.

Upon is a function from 3-tuples of ideas to ideas.
If the first argument idea is significant, that is,
non-nil, then the functional value is equal to the
second argument idea, otherwise it is equal to the
third argument idea.  Consequently, Upon functions
in the role of a conditional test and assignment.

function upon (thus, that, this: idea): idea;
var here: idea;
begin
 here := nil;
 if thus <> nil then here := that else here := this;
 upon := here
end;

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Obvert.

Obvert is a function from pairs of ideas to ideas.
Its functional value is identical to that of the
first argument idea.  Thus, Obvert functions in
the role of the first-coordinate projection of
its argument pair.

function obvert (that, this: idea): idea;
begin
 obvert := that
end;

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Revert.

Revert is a function from pairs of ideas to ideas.
Its functional value is identical to that of the
second argument idea.  Thus, Revert functions in
the role of the second-coordinate projection of
its argument pair.

function revert (that, this: idea): idea;
begin
 revert := this
end;

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Covert.

Covert is a function from pairs of ideas to ideas.
Its functional value is Upon the significance of
the first argument idea set equal to a nil idea,
otherwise set equal to the second argument idea.

function covert (that, this: idea): idea;
begin
 covert := upon (that, nil, this)
end;

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Divert.

Divert is a function from pairs of ideas to ideas.
Its functional value is Upon the significance of
the first argument idea set equal to the second
argument idea, otherwise set equal to nil.

function divert (that, this: idea): idea;
begin
 divert := upon (that, this, nil)
end;

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Equity.

Equity is a function from pairs of ideas to ideas.
Its functional value is a nil idea unless both of
its argument ideas are significant and identical
to each other, in which case its value is equal
to their common idea.

function equity (that, this: idea): idea;
var here: idea;
begin
 here := nil;
 if this <> nil then if that <> nil then
  if that = this then here := this;
 equity := here
end;

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inquiry e-lab: http://stderr.org/pipermail/inquiry/
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