Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!think.com!snorkelwacker.mit.edu!ai-lab!zurich.ai.mit.edu!jinx From: jinx@zurich.ai.mit.edu (Guillermo J. Rozas) Newsgroups: comp.lang.scheme Subject: Re: Explode/Implode Query Message-ID: Date: 22 Apr 91 19:36:42 GMT References: <1991Apr22.180734.21661@cunixf.cc.columbia.edu> Sender: news@ai.mit.edu Reply-To: jinx@zurich.ai.mit.edu Organization: M.I.T. Artificial Intelligence Lab. Lines: 47 In-reply-to: betsey@cunixf.cc.columbia.edu's message of 22 Apr 91 18:07:34 GMT In article <1991Apr22.180734.21661@cunixf.cc.columbia.edu> betsey@cunixf.cc.columbia.edu (Elizabeth Fike) writes: Path: ai-lab!mintaka!think.com!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!cunixf.cc.columbia.edu!betsey From: betsey@cunixf.cc.columbia.edu (Elizabeth Fike) Newsgroups: comp.lang.scheme Date: 22 Apr 91 18:07:34 GMT Sender: betsey@cunixf.cc.columbia.edu (Elizabeth Fike) Reply-To: betsey@cunixf.cc.columbia.edu Organization: Columbia University Lines: 14 Today, in my Scheme class, the professor mentioned the functions explode and implode, are found in PC-Scheme, but in no other current versions of Scheme. As these functions seem extremely useful, I am curious as to why they are not found in MIT Scheme version 7 (for example). Thanks in advance! /betsey "I think that God's got a sick sense of humor And when I die, I expect to find him laughing" --Depeche Mode, "Blasphemous Rumors" IMPLODE and EXPLODE are leftovers from older systems (MacLisp) that are referred to in SICP (Structure and Interpretation of Computer Programs by Abelson, Sussman, and Sussman), and (I believe) PC-Scheme included them in order to be compatible. MIT Scheme has evolved since the time when SICP was published and no longer provides them in the standard load. They are provided in the SICP compatibility package. MIT Scheme currently provides more useful alternatives. You may want to play with the following procedures: write-to-string with-output-to-string with-output-to-truncated-string with-string-output-port with-input-from-string string->input-port You can get the SICP compatibility package for MIT Scheme 7.1 from altdorf.ai.mit.edu:archive/scheme-7.1/sicp.tar.Z by anonymous ftp.