36 lines
1.1 KiB
Scheme
36 lines
1.1 KiB
Scheme
;; Call with standard output
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(print-int (current-output-port) 314159)
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;; Redirection to a file. Note that the port is automatically flushed
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;; (via force-output) before calling the C function, and that the C
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;; function gets a temporary "FILE" stream, which is closed after the
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;; call. So you can simply mix Scheme and C output.
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(with-output-to-file "test.out"
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(lambda ()
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(display 4711)
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(newline)
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(print-int (current-output-port) 314159)
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(display 815)
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(newline)))
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;; Redirection to a string or soft port won't work --
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;; we can only handle file ports.
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(catch #t
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(lambda ()
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(with-output-to-string
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(lambda ()
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(print-int (current-output-port) 314159))))
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(lambda args
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(display "Below shows that attempting to write to a string or soft port will result in a wrong-type-error...")
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(newline)
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(write args) (newline)))
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;; Read from a file port. Note that it is a bad idea to mix Scheme and
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;; C input because of buffering, hence the call to seek to rewind the file.
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(with-input-from-file "test.out"
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(lambda ()
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(seek (current-input-port) 0 SEEK_SET)
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(display (read-int (current-input-port)))
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(newline)))
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