@MIT-MC:eem@MIT-SYLVESTER (05/08/84)
From: Evangelos Milios <eem@sylvester> Domes Dedomenwn kai algorithmoi (HY240). O Manolis exei dikio otan leei oti i LISP krubei polles leptomereies apo ton xristi. Auto exei tis kakes epiptwseis pou anafere, alla kai tis kales, oti diladi ta programmata trexoun xwris pollous mpelades. Merikes apo tis diafores C kai LISP einai: 1) I LISP einai interactive kai object-oriented (diladi oi metablites (~ objects) joun mesa sto mixanima kai mporeis na tis exetaseis, na tis allaxeis, na tis kaneis oti theleis). I C einai compiled kai ta objects joun mono stigmiaia. Xreiazesai ena debugger gia na ta exetaseis, kai o debugger tou VAX-UNIX (dbx) exei arketa bugs akomi. 2) I C einai kali, alla exei merika problimata opws: Einai type-unsafe, idiws an xrisimopoieis pointers kai tous kaneis oti theleis. Sunithws kataligeis na katastrefeis to stack, pairnontas to mustirio minuma "memory fault, core dump" (UNIX trademark). Stin kaliteri periptwsi o debugger douleuei, kai briskeis grigora to lathos. Alles fores, o debugger den xerei ti na kanei kai pairneis ena allo endiaferon mustirio minuma. Sxetika me type safety, i Pascal einai arketa kaliteri apo tin C, alla exei ki auti tis tripes tis. 3) Stin LISP then xreiazesai pointers, dioti ta panta einai pointers. I timi mias metablitis mporei na einai arithmos, alla kai to onoma mias allis metablitis (diladi pointer). Stin Lisp uparxoun mixanismoi pou epitrepoun pollaplous pointers olous na xekinoun apo mia metabliti: property lists (the old-fashioned) i structures (opws stin C). Sunepws i pragmatopoiisi domwn dedomenwn (trees, linked lists, hashing tables, queues, stacks klp) einai sxetika apli. Ta parapanw den simainoun oti i C den einai kali glwssa genika, alla simainoun oti mathainetai diskolotera apo tin Lisp. To poia glwssa telika tha xrisimopoiithei sto HY240 exartatai fusika: (1) Apo ton didaskonta to mathima kai (2) to pneuma pou tha thelei na dwsei: an to mathima einai thewritiko, tote xarti kai molubi einai arketa, kai oi upologismoi xronou kai mnimis tha ginontai oloi me taxi megethous. An to mathima einai ergastiriakoeides, tote dialegoume metaxi C i Pascal (polu ergastiriako) kai LISP (ligo ergastiriako). Auto fernei sto proskinio ena allo thema, auto tou upologistikou exoplismou kai tou fortiou tou. To pws tha katanemithi o diathesimos xronos ston upologisti anamesa se ereuna, se didaskalia kai se poiwn mathimatwn tin didaskalia tha exartithei apo ton arithmo foititwn, ereunitwn kai ereunitikwn programmatwn. Se periptwsi stenotitas, nomizw oti to HY240 tha einai to prwto mathima pou tha metatrapei se thewritiko. ...Baggelis