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

[Jon Awbrey]

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Knap.

Knap is a transformation of ideas that acts as a predicate recognizer.
Its functional value is nil unless its argument idea points to a form
whose 'sign' field contains a right parenthesis and whose 'by'-field
addresses its own form, in which case the argument idea is returned
as the functional value.  The following figure shows the type of
configuration that is required for a non-nil result.

  o---------o
  |  o---o  |
  o->| ) |--o
     o---o
     ^
this | = knap (this)
     @

function knap (this: idea): idea;
begin
 knap := equity (next (this), rest (this))
end;

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