Examples 

  \begin{evaltrace}
  +--> ;(++ 2 3)
  |
  |  +--> ;2                  {\it First argument evaluates to itself.}
  |  |
  |  +_-> ;2
  |
  |  +--> ;3                  {\it Second argument evaluates to itself.}
  |  |
  |  +_-> ;3
  |
  +**> ;Apply ++ to 2 and 3    {\it Apply the function to its arguments.}
  *
  +_*> ;5
  \end{evaltrace}
produces
\begin{evaltrace} +--> ;(++ 2 3) \vert \vert +--> ;2 {\it First argument evaluat... ... to 2 and 3 {\it Apply the function to its arguments.} * +_*> ;5 \end{evaltrace}

Asterisks produce thick solid lines. Notice that the semi-colon and special + characters don't take up any space on output, so this affects the placement of the italicized comments in getting them to line up correctly. 

  \begin{evaltrace}
  +--> ;(double (++ 3 5))
  |
  |  +--> ;(++ 3 5)
  |  |
  |  +_-> ;8
  |
  +**> ;Apply DOUBLE to 8
  *    ;create local variable N with value 8
  *
  *  +--> ;(* n 2)
  *  | "n"-->"8"
  *  | "2"-->"2"
  *  +_-> ;16
  +_*> ;Result of DOUBLE is 16
  \end{evaltrace}
results in
\begin{evaltrace} +--> ;(double (++ 3 5)) \vert \vert +--> ;(++ 3 5) \vert \vert... ...'' * \vert ''2''-->''2'' * +_-> ;16 +_*> ;Result of DOUBLE is 16 \end{evaltrace}

Here, another special character, the double-quote ("), is used to once again produce teletype output. Unlike, semi-colon, this each double-quote does take up one column of space. This is convenient in closure diagrams, as shown in a figure below.

The sequence +**> produces an upper thick arrow with a thin spur, T]. 

  \begin{evaltrace}
  +--> ;(average 3 7)
  |
  +**> ;Apply AVERAGE to 3 and 7
  *    ;create local variable X with value 3
  *    ;create local variable Y with value 7
  *
  *  +--> ;(let ((sum ...)) ...)
  *  |   +--> ;(++ x y)
  *  |   |
  *  |   +_-> ;10
  *  +%%> ;Enter LET body
  *  %    ;create local variable SUM with value 10
  *  %
  *  %  +--> ;(list x y 'average (/ sum 2))
  *  %  | "x"-->"3"
  *  %  | "y"-->"7"
  *  %  | "'average"-->"AVERAGE"
  *  %  |  +--> ;(/ sum 2)
  *  %  |  | "sum"-->"10"
  *  %  |  +_-> ;5
  *  %  +_-> ;(3 7 average 5)
  *  +_%> ;(3 7 average 5)
  +_*> ;Result of AVERAGE is (3 7 AVERAGE 5)
  \end{evaltrace}
produces
\begin{evaltrace} +--> ;(average 3 7) \vert +**> ;Apply AVERAGE to 3 and 7 * ;cr... ... ;(3 7 average 5) * +_+_*> ;Result of AVERAGE is (3 7 AVERAGE 5) \end{evaltrace} 

  \begin{evaltrace}
  +--> ;(price-change 'widgets 1.25 1.35)
  |
  +**> ;Apply PRICE-CHANGE to WIDGETS, 1.25 and 1.35
  *    ;create local variable NAME with value WIDGETS
  *    ;create local variable OLD with value 1.25
  *    ;create local variable NEW with value 1.35
  *  +--> ;(let ...)
  *  |  +--> ;(- new old)
  *  |  | "new"-->"1.35"
  *  |  | "old"-->"1.25"
  *  |  +_-> ;0.10
  *  |
  *  |  +--> ;(/ diff old)
  *  |  |
  A_]a->+_-> ;Error!  DIFF unassigned variable.
  \end{evaltrace}
results in
\begin{evaltrace} +--> ;(price-change 'widgets 1.25 1.35) \vert +**> ;Apply PRIC... ... old) * \vert \vert A_]a->+_-> ;Error! DIFF unassigned variable. \end{evaltrace}

Here, in order to get the bottom arrows to run into each other, we use the raw et font character mappings. 

  \begin{evaltrace}
  +--> ;(price-change 'widgets 1.25 1.35)
  |
  +**> ;Apply PRICE-CHANGE to 1.25 and 1.35
  *    ;create local variable NAME with value WIDGETS
  *    ;create local variable OLD with value 1.25
  *    ;create local variable NEW with value 1.35
  *  +--> ;(let* ...)
  *  |  +--> ;(- new old)
  *  |  |
  *  |  +_-> ;0.10
  *  +%%> ;Enter LET body
  *  %    ;create local variable DIFF with value 0.10
  *  %  +--> ;(/ diff old)
  *  %  |
  *  %  +_-> ;0.08
  *  %  +==> ;Enter LET body
  *  %  %    ;create local variable PROPORTION with value 0.08
  *  %  %  +--> ;(* proportion 100.0)
  *  %  %  |
  *  %  %  +_-> ;8.0
  *  %  %  +==> ;Enter LET body
  *  %  %  %    ;create local variable PERCENTAGE with value 8.0
  *  %  %  %  +--> ;(list name 'changed 'by percentage 'percent)
  *  %  %  %  |
  *  %  %  %  +_-> ;(WIDGETS CHANGED BY 8.0 PERCENT)
  *  D=!D=!+_%> ;(WIDGETS CHANGED BY 8.0 PERCENT)
  +_*> ;Result of PRICE-CHANGE is (WIDGETS CHANGED BY 8.0 PERCENT)
  \end{evaltrace}
produces
\begin{evaltrace} +--> ;(price-change 'widgets 1.25 1.35) \vert +**> ;Apply PRIC... ...+_*> ;Result of PRICE-CHANGE is (WIDGETS CHANGED BY 8.0 PERCENT) \end{evaltrace}

Again, notice the use of the et font. 

  \begin{evaltrace}
  +--> ;(zero-center '(3 11 13))
  |
  +**> ;Apply ZERO-CENTER to (3 11 13)
  *    ;create local variable DATA with value (3 11 13)
  *  +--> ;(let ...)
  *  | "(average data)"-->"9"
  *  +%%> ;Enter LET body
  *  %    ;create local variable AVG with value 9
  *  %  +--> ;(mapcar #'(lambda (x) (- x avg)) data)
  *  %  |  +--> ;#'(lambda (x) (- x avg))
  *  %  |  |
  *  %  |  +_-> ;#<Lexical-closure A>
  *  %  | "data"-->"(3 11 13)"
  *  %  +**> ;Apply MAPCAR to #<Lexical-closure A> and (3 11 13)
  *  %  *
  *  %  *  +==> ;Apply #<Lexical-closure A> to 3
  *  %  *  %    ;create local variable X with value 3
  *  %<----/  +--> ;(- x avg)
  *  %  *  %  |
  *  %  *  %  +_-> ;-6
  *  %  *  +_%> ;-6
  *  %  *
  *  %  *  +==> ;Apply #<Lexical-closure A> to 11
  *  %  *  %    ;create local variable X with value 11
  *  %<----/  +--> ;(- x avg)
  *  %  *  %  |
  *  %  *  %  +_-> ;2
  *  %  *  +_%> ;2
  *  %  *
  *  %  *  +==> ;Apply #<Lexical-closure A> to 13
  *  %  *  %    ;create local variable X with value 13
  *  %<----/  +--> ;(- x avg)
  *  %  *  %  |
  *  %  *  %  +_-> ;4
  *  %  *  +_%> ;4
  *  %  +_*> ;Result of MAPCAR is (-6 2 4)
  *  +_%> ;(-6 2 4)
  +_*> ;Result of ZERO-CENTER is (-6 2 4)
  \end{evaltrace}
results in
\begin{evaltrace} +--> ;(zero-center '(3 11 13)) \vert +**> ;Apply ZERO-CENTER t... ...f MAPCAR is (-6 2 4) * +_+_*> ;Result of ZERO-CENTER is (-6 2 4) \end{evaltrace}

Notice the use of the special connecting-line character. 

  \begin{evaltrace}
                  +--> ;(zero-center '(3 11 13))
                  |
                  +**> ;Apply ZERO-CENTER to (3 11 13)
                  *    ;create local variable DATA with value (3 11 13)
                  *  +--> ;(mapcar (shifter (average data)) data)
                  *  |  +--> ;(shifter (average data))
                  *  |  | "(average data)"-->"9"
                  *  |  +**> ;Apply SHIFTER to 9
                  *  |  *    ;create local variable KONST with value 9
                  *  |  *  +--> ;#'(lambda (x) (- x konst))
        e..................'
        :         *  |  *  +_-> ;#<Lexical-closure A>
        v         *  |  +_*> ;Result of SHIFTER is #<Lexical-closure A>
  q-----------w   *  | "data"-->"(3 11 13)"
  |           |   *  +**> ;Apply MAPCAR to #<Lexical-closure A>, (3 11 13)
  |"KONST = 9"|   *  *
  |           |   *  *  +==> ;Apply #<Lexical-closure A> to 3
  a-----------s   *  *  %    ;create local variable X with value 3
        ^         *  *  %  +--> ;(- x konst)
        |         *  *  %  |
        a---------------/  +_-> ;-6
        ^         *  *  +_%> ;-6
        |         *  *
        |         *  *  +==> ;Apply #<Lexical-closure A> to 11
        |         *  *  %    ;create local variable X with value 11
        |         *  *  %  +--> ;(- x konst)
        a---------------/  |
        ^         *  *  %  +_-> ;2
        |         *  *  +_%> ;2
        |         *  *
        |         *  *  +==> ;Apply #<Lexical-closure A> to 13
        |         *  *  %    ;create local variable X with value 13
        |         *  *  %  +--> ;(- x konst)
        a---------------/  |
                  *  *  %  +_-> ;4
                  *  *  +_%> ;4
                  *  +_*> ;Result of MAPCAR is (-6 2 4)
                  +_*> ;Result of ZERO-CENTER is (-6 2 4)
  \end{evaltrace}
produces
\begin{evaltrace} +--> ;(zero-center '(3 11 13)) \vert +**> ;Apply ZERO-CENTE... ...t of MAPCAR is (-6 2 4) +_*> ;Result of ZERO-CENTER is (-6 2 4) \end{evaltrace} 

  \begin{evaltrace}
  ;{\it the global variable A has value FOO}
  \strut
  +--> ;(test 5)
  |
  +**> ;Apply TEST to 5
  *    ;create local variable A with value 5
  *  +..> ;(simple-incf a)
  *  :  +__> ;Apply macro SIMPLE-INCF to A
  *  :  *    ;create local variable VAR with value A
  *  :  *  +--> ;(print a)
  *  :  *  | "a"-->"FOO"
  *  :  *  |      ;print FOO
  *  :  *  +_-> ;FOO
  *  :  *  +--> ;(list 'setq var (list '++ var 1))
  *  :  *  |
  *  :  *  +_-> ;(SETQ A (++ A 1))
  *  :  +_*> ;Result of macro expansion is (SETQ A (++ A 1))
  *  +.-> ;(setq a (++ a 1))
  *  | "(++ a 1)"-->"6"
  *  |     ;set local variable A to 6
  *  +_-> ;6
  +_*> ;Result of TEST is 6
  \end{evaltrace}
results in
\begin{evaltrace} ;{\it the global variable A has value FOO} \strut +--> ;(test ... ...t ;set local variable A to 6 * +_-> ;6 +_*> ;Result of TEST is 6 \end{evaltrace}