[Inquiry] Re: Theme One Program -- Commentary Notes

[Jon Awbrey]

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TOP.  Commentary Note 19

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Class.

Class is transformation of ideas that serves as a special-purpose modifier.
If the argument idea is non-nil and therefore points to an existing form,
then Class resets the 'sign' field of this form in accord with a certain
semantic equivalence relation, specifically, one in which a comma is the
canonical sign for the semantic equivalence class {blank, enter, comma}
and a period is the canonical sign for the semantic equivalence class
{escap, ender, point}.  This function is used at several points in
the Theme One program by way of responding to command keystrokes
whose operational meanings are equivalent at those points.

function class (this: idea): idea;
begin
 class := this;
 if this <> nil then
  case arch (this) of
   blank, enter: this := scrip (this, comma);
   escap, ender: this := scrip (this, point)
  end
end;

(5258)(7598)

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Clash.

Clash is mapping from texts and ideas to (texts and) ideas that functions
as a special-purpose input-output echo.  If the argument idea is non-nil
and therefore points to an existing form, then Clash writes the canonical
representative of its 'sign' field to the argument text file, normally the
screen, in accord with the appropriate semantic equivalence relation, where
a left parenthesis is the canonical sign for the semantic equivalence class
{comma, left parenthesis} and a right parenthesis is the canonical sign for
the semantic equivalence class {period, right parenthesis}.  This function
is used at several points in the Theme One program to deal with command
keystrokes whose operational meanings are equivalent at those points.

function clash (var thou: text;
                    this: idea): idea;
begin
 clash := this;
 if this <> nil then
  case arch (this) of
   comma: this := pass (thou, links, this);
   point: this := pass (thou, right, this)
  end
end;

(5259)(7599)

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