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About the choice of Pascal for TeX in 1980… was it the case that Pascal was the most widely available language at the time (at least at universities and the lik

by svat 6y ago

About the choice of Pascal for TeX in 1980… was it the case that Pascal was the most widely available language at the time (at least at universities and the like where TeX would be used)? Is that why Pascal was chosen as the language for the "portable" TeX rewrite? Or was it just that Pascal was available for PDP-10 (was that a common computer?) and reasonably easy to translate from, so it was a good base? About some of the other issues (system calls, a default for "case", etc), isn't it the case that most Pascal installations did have their own extensions that resolved this (even before Turbo Pascal)? (I'm actually surprised how many distinct Pascal compilers there seem to have been, with their own extensions… it must have been a language easy to write compilers for, which must explain some of its rapid popularity.) So some of this was more a failure of standardization (Wirth just didn't think about these factors enough to put them in the original standard, or update the standard fast enough) rather than non-availability in the Pascal that anyone used at a particular place. (Of course they'd become issues for porting programs over to another system.)

drfuchs 6y ago
At the time, Knuth was exclusively using a PDP-10, "SAIL", running the WAITS time-share operating system. If you look at early ARPAnet maps, you'll see that maybe half of the machines were DEC PDP-20's; certainly at Stanford, MIT, CMU, etc., the first machines to be connected to (what was to become) the Internet were. One main goal of the 1980's TeX rewrite was to make it as portable as possible, to support other popular architectures of the day. C wasn't available for DEC PDP mainframes; IBM 360s didn't have a C compiler at the time, either. PL/I, Algol, etc. were also not universally available. So, based on the fact that the Hedrick Pascal compiler existed for the PDPs, and a general notion that a reasonable Pascal was, or would soon, be available for VAX/VMS, IBM, and Unix (the gpc front-end for gcc), the choice was made. By the way, at the time it didn't seem like PCs and Macs would be viable platforms, being so memory-constrained (TeX wanted a whole megabyte to run in!) so that wasn't a big part of the consideration. And Unix workstations (Sun, HP, etc.) weren't yet really a thing yet. It wasn't a super-comfortable decision, but seemed like the best choice at the time. Partly because of this, TeX is written to use just a subset of the Pascal language, so as to keep things simple, and thus ultimately translatable into other languages if necessary. It turned out that DEC eventually made a very good Pascal compiler for VMS, and similarly for IBM; but GPC lagged, and the popular Unix ports of TeX are based on C translations of TeX's Pascal code. Ditto for (all? some?) of the PC and Mac versions. But, to your point, yes, all the various compilers of the time had their own work-arounds to the "default", "fopen", etc. problems. The fact that they chose different syntaxes wasn't a big issue, being easily addressable via the "WEB" macro language Knuth wrote on top of. Much more of a pain was Pascal's virtually useless string functionality and poor memory-management that required laborious work-arounds, resulting in code that is difficult to modify and debug. It's a real shame that standardization of the features needed to make Pascal a language that was really suitable for cross-platform production code didn't happen in time to make a difference. All of the code Knuth writes has been in C (via CWEB) for quite some time now. [Edit: tried to say "star"-nix, but that made everything \it, so switched to "Unix".]

by svat 6y ago

drfuchs 6y ago

At the time, Knuth was exclusively using a PDP-10, "SAIL", running the WAITS time-share operating system. If you look at early ARPAnet maps, you'll see that maybe half of the machines were DEC PDP-20's; certainly at Stanford, MIT, CMU, etc., the first machines to be connected to (what was to become) the Internet were. One main goal of the 1980's TeX rewrite was to make it as portable as possible, to support other popular architectures of the day. C wasn't available for DEC PDP mainframes; IBM 360s didn't have a C compiler at the time, either. PL/I, Algol, etc. were also not universally available. So, based on the fact that the Hedrick Pascal compiler existed for the PDPs, and a general notion that a reasonable Pascal was, or would soon, be available for VAX/VMS, IBM, and Unix (the gpc front-end for gcc), the choice was made. By the way, at the time it didn't seem like PCs and Macs would be viable platforms, being so memory-constrained (TeX wanted a whole megabyte to run in!) so that wasn't a big part of the consideration. And Unix workstations (Sun, HP, etc.) weren't yet really a thing yet. It wasn't a super-comfortable decision, but seemed like the best choice at the time. Partly because of this, TeX is written to use just a subset of the Pascal language, so as to keep things simple, and thus ultimately translatable into other languages if necessary. It turned out that DEC eventually made a very good Pascal compiler for VMS, and similarly for IBM; but GPC lagged, and the popular Unix ports of TeX are based on C translations of TeX's Pascal code. Ditto for (all? some?) of the PC and Mac versions. But, to your point, yes, all the various compilers of the time had their own work-arounds to the "default", "fopen", etc. problems. The fact that they chose different syntaxes wasn't a big issue, being easily addressable via the "WEB" macro language Knuth wrote on top of. Much more of a pain was Pascal's virtually useless string functionality and poor memory-management that required laborious work-arounds, resulting in code that is difficult to modify and debug. It's a real shame that standardization of the features needed to make Pascal a language that was really suitable for cross-platform production code didn't happen in time to make a difference. All of the code Knuth writes has been in C (via CWEB) for quite some time now. [Edit: tried to say "star"-nix, but that made everything \it, so switched to "Unix".]