Function call error Scheme -


i'm using https://repl.it/languages/scheme compile scheme code , i'm running function call errors. function is: 

 (define (bloop x)       (cond         ((null? x) 0)         ((not (list? (car x)))              (+ 1 (bloop (cdr x))))         ((eq? x ’()) (bloop (car x)))))

i want pass like: 

(bloop '((1) 2 3 4))

but get: 

error: execute: unbound symbol: "’"

any comment, question or concern appreciated.

in line:

((eq? x ’()) (bloop (car x)))))

the ’ symbol not ascii quotation '.

ps. in scheme jargon bloop procedure. function mathematical, "sin(x)", (sin x) procedure implementing function.


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