I recently decided to start playing with MIT Scheme by following along with the examples in SICP. I installed scheme from the Ubuntu repository.
sudo apt-get install mit-scheme
Given an input file that looks like this:
486
(+ 137 349)
(- 1000 334)
(* 5 99)
(/ 10 5)
(* 25 4 12)
I run scheme as follows.
scheme < Numbers.scm
It produces the following output.
MIT/GNU Scheme running under GNU/Linux
Type `^C' (control-C) followed by `H' to obtain information about interrupts.
Copyright (C) 2011 Massachusetts Institute of Technology
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Image saved on Sunday February 7, 2016 at 10:35:34 AM
Release 9.1.1 || Microcode 15.3 || Runtime 15.7 || SF 4.41 || LIAR/x86-64 4.118 || Edwin 3.116
1 ]=> 486
;Value: 486
1 ]=> (+ 137 349)
;Value: 486
1 ]=> (- 1000 334)
;Value: 666
1 ]=> (* 5 99)
;Value: 495
1 ]=> (/ 10 5)
;Value: 2
1 ]=> (* 25 4 12)
;Value: 1200
1 ]=>
End of input stream reached.
Moriturus te saluto.
This output feels excessive, so I'm currently paring it down like so.
scheme < Numbers.scm | awk '/Value/ {print $2}
486
486
666
495
2
1200
Is there a native way to reduce the verbosity of scheme, so I can get something resembling the above output without resorting to an external process?
I have examined the output of scheme --help
but did not find any obvious options.
Note that passing the filename as an argument does not appear to work in MIT-Scheme.
scheme Numbers.scm
MIT/GNU Scheme running under GNU/Linux
Type `^C' (control-C) followed by `H' to obtain information about interrupts.
Copyright (C) 2011 Massachusetts Institute of Technology
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Image saved on Sunday February 7, 2016 at 10:35:34 AM
Release 9.1.1 || Microcode 15.3 || Runtime 15.7 || SF 4.41 || LIAR/x86-64 4.118 || Edwin 3.116
;Warning: Invalid keyword: "Numbers.scm"
;Warning: Unhandled command line options: ("Numbers.scm")
1 ]=>
Here you go:
scheme --quiet < Numbers.scm
Now this will suppress the REPL entirely except when errors occur so that what is not explicitly displayed will not be displayed. eg. evaluatiing (+ 2 3)
returns 5
, but does not print since you have not told it to print. You need to use procedures like display
to get the information printed or go back to using a REPL which sole purpose is to display your results.
I was originally hoping you could do:
scheme --quiet --load Numbers.scm
But it does not exit after the file and adding --eval (exit)
has the REPL ask if you want to quit.
EDIT
(define (displayln v)
(display v)
(newline)
v)
(displayln (+ 4 5))
; ==> 9, in addition you get the side effect that "9\n" is written to current output port
You could also perhaps make a macro to do this:
(define-syntax begin-display
(syntax-rules ()
((_ form ...) (begin (displayln form) ...))))
(begin-display
486
(+ 137 349)
(- 1000 334)
(* 5 99)
(/ 10 5)
(* 25 4 12))
; ==> 1200. In addition you get the side effect that "486\n486\n666\n49\n2\n1200\n" is written to current output port