from R6RS
(apply proc arg1 . . . rest-args)

Rest-args must be a list. Proc should accept n arguments, where n is number of args plus the length of rest-args. The apply procedure calls proc with the elements of the list
(append (list arg1 . . . ) rest-args )
as the actual arguments.

Hi,
Can you help adding a license to let users know how/if they can use the code?

See
https://help.github.com/articles/adding-a-license-to-a-repository/
https://choosealicense.com/

(parameterize
((current-output-port
(open-output-string)))
(display "piece")
(display " by piece ")
(display "by piece.")
(newline)
(get-output-string (current-output-port)))
=⇒ "piece by piece by piece.\n"

while debugging it would help to see the S-Expression tree.
The S-Expression viewer logic should be re-implemented as a debugger script

TO DO:

• quasiquote ` (currently works as quote ')
• unquote ,
• unquote-splicing ,@

http://www.iro.umontreal.ca/~feeley/papers/PierardFeeleySW07.pdf

Implementation and unit test created. Tests fails.

ports, input, output
Create classes implementing different input/output port:

• from file
• from CL_DEMO_OUTPUT

Enable selection/switch between console implementations - to be extended to accept opt. parameter

(display obj)
(display obj port)

(write obj)
(write obj port)

(newline)
(newline port)

(input-port? obj)
(output-port? obj)
(textal-port? obj)
(binary-port? obj)
(port? obj)

(input-port-open? obj)
(output-port-open? obj)

(current-input-port)
(current-output-port)
(current-error-port)

(close-port port)
(close-input-port port)
(close-output-port port)

(open-input-string string)
(open-output-string)
(get-output-string port)

;; deferred to new issue
(parameterize
((current-output-port
(open-output-string)))
(display "piece")
(display " by piece ")
(display "by piece.")
(newline)
(get-output-string (current-output-port)))
=⇒ "piece by piece by piece.\n"

(read)
(read port)

(read-char)
(read-char port)

(peek-char)
(peek-char port)

(char-ready?)
(char-rea

(let ''name'' (''bindings'') ''body'')

e.g.

  (let sum ((lst (list 1 2 3))
            (s 0))
    (if (null? lst)
        s
        (sum (cdr lst) (+ s (car lst)))))

https://www.scheme.com/tspl4/examples.html#./examples:h9

If abapGit fails with a Shared Memory issue,
start transaction SHMA, enter Area Name ZCL_LISP_AREA and press the "Generate area class" icon (Ctrl+F3). You can then repeat the installation.

The developer should be able to define a maximal execution time for any ABAP Scheme Evaluation. If the time needed is larger, a TIME_OUT should occurs within the Workbench without ABAP Short Dump

ABAP Unit can also Limit the execution time of an ABAP Unit test. This is the functionality to replicate

Class CL_AUNIT_CLASSTEST_SESSIONFE
Method __CANCEL_RFC

Iterations are already possible with named let,
TO DO: do special form

    (do (( <variable1> <init1> <step1>) 
    . . . )
    (<testi> <expressioni> . . . )
    <commandi> . . . )

check Racket syntax
https://docs.racket-lang.org/sql/index.html

http://dept-info.labri.fr/~strandh/Teaching/PFS/Common/Strandh-Tutorial/indentation.html

||
|HelloWorld| are valid identifier that are not recognized by the parser yet

The Code was verified under Netweaver 7.4 SP9

in R7RS, a body is made of 0 or more declarations followed by expressions, so

• internal defines must be placed before any expression
• multiple define for the same variable are not allowed.

So the following programs should be wrong:

  (define (foo)
    (display 1)       ; not allowed before define
    (define bar 1)
    bar)

  (define (foo)
    (define bar 1)
    (define bar 2)   ; redefinition not allowe
    bar)

Top-level definitions do not have this restriction.

Currently it possible to create a pair with cons
(cons a b) => ( a . b )
but
'( a . b ) will not work.

Tail Cail Optimization is not supported yet