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i have some task that ask me to create a list in LISP , so I'm using clips online and I made this code the create my list and do some operations

‭‬‬‬‬
‭(‬print‭ (‬setq y‭ '(‬2‭ ‬3‭ ‬4‭ ‬5‭ ‬6‭ ‬7‭ ‬8‭)))‬‬‬‬‬‬‬‬‬‬‬
‭(‬print‭  (‬setq y‭ (‬cons 1‭ ‬y‭)))‬‬‬‬‬‬
‭(‬print‭  (‬setq y‭ (‬append y‭ '(‬9‭))))‬‬‬‬‬‬
‭(‬print‭  (‬car y‭))‬‬‬‬
‭(‬print‭  (‬second y‭))‬‬‬‬
‭(‬print‭  (‬third y‭))‬‬‬‬
‭(‬print‭  (‬fourth y‭))‬‬‬‬
‭(‬print‭  (‬fifth y‭))‬‬‬‬
‭(‬print‭  (‬last y‭))‬‬‬‬
‭(‬print‭ (‬second‭ (‬reverse y‭)))‬‬‬‬‬
‭(‬print‭  (‬setq y‭ (‬reverse y‭)))‬‬‬‬‬
‭(‬print‭  (‬setq y‭ (‬cdr y‭)))‬‬‬‬‬
‭(‬print‭  (‬setq y‭ (‬reverse‭ (‬cdr‭ (‬reverse y‭)))))‬‬‬‬‬‬‬
‭(‬print‭  (‬length y‭))‬‬‬‬
‭(‬print‭  (‬member 9‭ ‬y‭))‬‬‬‬‬

and this error appears without any other output:

*** - EVAL: variable ‭‬‬‬‬ has no value

can you please help me understand what's wrong and what to do? thank you

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1 Answer 1

Reset to default
3

you should ask yourself why your code contains non-printing characters. Just try again to use a program without hidden characters.

> (length "‭(‬print‭ (‬setq y‭ '(‬2‭ ‬3‭ ‬4‭ ‬5‭ ‬6‭ ‬7‭ ‬8‭)))‬‬‬‬‬‬‬‬‬‬‬")
63

without hidden characters:

> (length "(print (setq y '(2 3 4 5 6 7 8)))")
33

As Bruno Haible mentioned, we can see it more clearly:

[1]> (coerce "(‬print‭ (‬setq y‭ '(‬2‭ ‬3‭ ‬4‭ ‬5‭ ‬6‭ ‬7‭ ‬8‭)))‬‬‬‬‬‬‬‬‬‬‬" 'list)
(#\( #\POP_DIRECTIONAL_FORMATTING #\p #\r #\i #\n #\t #\LEFT-TO-RIGHT_OVERRIDE #\Space #\( #\POP_DIRECTIONAL_FORMATTING #\s #\e #\t #\q #\Space #\y #\LEFT-TO-RIGHT_OVERRIDE #\Space #\' #\( #\POP_DIRECTIONAL_FORMATTING #\2
 #\LEFT-TO-RIGHT_OVERRIDE #\Space #\POP_DIRECTIONAL_FORMATTING #\3 #\LEFT-TO-RIGHT_OVERRIDE #\Space #\POP_DIRECTIONAL_FORMATTING #\4 #\LEFT-TO-RIGHT_OVERRIDE #\Space #\POP_DIRECTIONAL_FORMATTING #\5 #\LEFT-TO-RIGHT_OVERRIDE
 #\Space #\POP_DIRECTIONAL_FORMATTING #\6 #\LEFT-TO-RIGHT_OVERRIDE #\Space #\POP_DIRECTIONAL_FORMATTING #\7 #\LEFT-TO-RIGHT_OVERRIDE #\Space #\POP_DIRECTIONAL_FORMATTING #\8 #\LEFT-TO-RIGHT_OVERRIDE #\) #\) #\)
 #\POP_DIRECTIONAL_FORMATTING #\POP_DIRECTIONAL_FORMATTING #\POP_DIRECTIONAL_FORMATTING #\POP_DIRECTIONAL_FORMATTING #\POP_DIRECTIONAL_FORMATTING #\POP_DIRECTIONAL_FORMATTING #\POP_DIRECTIONAL_FORMATTING
 #\POP_DIRECTIONAL_FORMATTING #\POP_DIRECTIONAL_FORMATTING #\POP_DIRECTIONAL_FORMATTING #\POP_DIRECTIONAL_FORMATTING)
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1 Comment

You can see the hidden characters by executing (coerce "(‬print‭ (‬setq y‭ '(‬2‭ ‬3‭ ‬4‭ ‬5‭ ‬6‭ ‬7‭ ‬8‭)))‬‬‬‬‬‬‬‬‬‬‬" 'list).

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