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From: Jens Kallup <paule32.jk@gmail.com>
Newsgroups: comp.lang.lisp
Subject: Re: Rather simple list/set operation [?]
Date: Fri, 7 Jun 2024 21:36:44 +0200
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(Common) LISP/SBCL

essential structure consists of two fields (or: one left hand field, and
one right hand field), which can extend trough other (same) fields of
the given field pair.

The lhs of the first form can be see as reference to it self or as start
point, that contain a pointer to the next form, which is represented on
the rhs.

You can cocoon this by other functions and/or commands/keywords, ...

=> here is an example: (1 2)
   this is a simple form of a list, containing 1 and 2.

=> here is an example: (+ 2 1)
   - this is a simple form of a operation,
   - the + sign after the first paren is a "addition" function, that
     take the first number from right (the 1) will be evaluate first,
     and the add (+) symbol (which is a function) "signs" that the
     next coming number (the 2) should be added to the (before eval 1)
     so, you get as result the three (3).

=> each operation/command/task must have two objects, except, you call
   a non-parameterized function or you build a list.

If you evaluate only one form, then you could be get a error message.
Or, if you evaluate a boolean value false (which is in LISP = nil) or
a boolean value true (wich is in LISP the single symbol T ).

You can create dictionaries by paring two elements or forms, where you
give a key on the left side, and a value on the right hand side:

(A . 1)  or:  (U . 3)

Jens