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

[Jon Awbrey]

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TOP.  Commentary Note 13

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Arch.

Arch is the 'sign' selector with respect
to the idea-form construct, and as such
a function from ideas to characters.

If 'this' is a nil idea, then arch (this) is the blank character (" ").
If 'this' is a non-nil idea, and therefore points to an existing form,
then arch (this) = this^.sign.

For example, if this = peg ("a", p, q, r, s, 1),
as shown in the picture, then arch (this) = "a".

   ^ ^     ^
   p\|q   r|
     o-----o s 
     | a 1 |--->
     o-----o
     ^
this |
     @

function arch (this: idea): char;
var mark: char;
begin
 mark := blank;
 if this <> nil then mark := this^.sign;
 arch := mark
end;

(5230)(7570)

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Ante.

Ante is the 'as'-field selector with respect to
the idea-form construct, and as such a function
from ideas to ideas.

If 'this' is a nil idea, then ante (this) is also nil.
If 'this' is a non-nil idea, and therefore points to
an existing form, then ante (this) = this^.as.

For example, if this = peg ("a", p, q, r, s, 1),
as depicted in the figure, then ante (this) = p.

   ^ ^     ^
   p\|q   r|
     o-----o s 
     | a 1 |--->
     o-----o
     ^
this |
     @

function ante (this: idea): idea;
var here: idea;
begin
 here := nil;
 if this <> nil then here := this^.as;
 ante := here
end;

(5231)(7571)

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Nigh.

Nigh is the 'up'-field selector with respect to
the idea-form construct, and as such a function
from ideas to ideas.

If 'this' is a nil idea, then nigh (this) is also nil.
If 'this' is a non-nil idea, and therefore points to
an existing form, then nigh (this) = this^.up.

For example, if this = peg ("a", p, q, r, s, 1),
as depicted in the figure, then nigh (this) = q.

   ^ ^     ^
   p\|q   r|
     o-----o s 
     | a 1 |--->
     o-----o
     ^
this |
     @

function nigh (this: idea): idea;
var here: idea;
begin
 here := nil;
 if this <> nil then here := this^.up;
 nigh := here
end;

(5232)(7572)

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Trip.

Trip is the 'on'-field selector with respect to
the idea-form construct, and as such a function
from ideas to ideas.

If 'this' is a nil idea, then trip (this) is also nil.
If 'this' is a non-nil idea, and therefore points to
an existing form, then trip (this) = this^.on.

For example, if this = peg ("a", p, q, r, s, 1),
as depicted in the figure, then trip (this) = r.

   ^ ^     ^
   p\|q   r|
     o-----o s 
     | a 1 |--->
     o-----o
     ^
this |
     @

function trip (this: idea): idea;
var here: idea;
begin
 here := nil;
 if this <> nil then here := this^.on;
 trip := here
end;

(5233)(7573)

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Next.

Next is the 'by'-field selector with respect to
the idea-form construct, and as such a function
from ideas to ideas.

If 'this' is a nil idea, then next (this) is also nil.
If 'this' is a non-nil idea, and therefore points to
an existing form, then next (this) = this^.by.

For example, if this = peg ("a", p, q, r, s, 1),
as depicted in the figure, then next (this) = s.

   ^ ^     ^
   p\|q   r|
     o-----o s 
     | a 1 |--->
     o-----o
     ^
this |
     @

function next (this: idea): idea;
var here: idea;
begin
 here := nil;
 if this <> nil then here := this^.by;
 next := here
end;

(5234)(7574)

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Reck.

Reck is the 'code' selector with respect
to the idea-form construct, and as such
is a function from ideas to integers.

If 'this' is a nil idea, then reck (this) is assigned a value of zero.
If 'this' is a non-nil idea, and therefore points to an existing form,
then reck (this) = this^.code.

For example, if this = peg ("a", p, q, r, s, 1),
as depicted in the figure, then reck (this) = 1.

   ^ ^     ^
   p\|q   r|
     o-----o s 
     | a 1 |--->
     o-----o
     ^
this |
     @

function reck (this: idea): numb;
var what: numb;
begin
 what := 0;
 if this <> nil then what := this^.code;
 reck := what
end;

(5235)(7575)

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