16 lines
497 B
Scheme
16 lines
497 B
Scheme
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(library (ikarus strings)
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(export string-ref)
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(import
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(except (ikarus) string-ref)
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(only (scheme) $string-ref $fx<= $fx< $string-length))
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(define (string-ref s i)
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(unless (string? s)
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(error 'string-ref "~s is not a string" s))
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(unless (fixnum? i)
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(error 'string-ref "~s is not a valid index" i))
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(unless (and ($fx< i ($string-length s))
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($fx<= 0 i))
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(error 'string-ref "index ~s is out of range for ~s" i s))
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($string-ref s i)))
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