10 Mar
2025
10 Mar
'25
2:28 a.m.
[While walking 5 miles through the snow …]
On Mar 9, 2025, at 9:03 PM, Douglas McIlroy
<douglas.mcilroy(a)dartmouth.edu> wrote:
In 1971 compiler construction course at UT-Austin, we had to use CDC Fortran to build a
compiler for a subset of Algol 60. Undergraduates used punch cards and RJE to the
6600/6400 shared by all but the privleged few.
Charlie
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everyone should write for their first compiler in
Pascal for a
simple language and no cheating using YACC. You need to write the whole
thing if you want to understand how parsing really works.
Yacc certainly makes it easier to write parsers for big grammars, but it's far from
cheating. You need to know a lot more about parsing to use Yacc than you need to roll your
own.
Hand parsing of a tiny grammar is almost a necessary step on the way to understanding
Yacc. But I think hand-building the whole parser for a compiler is unnecessary
torture--like doing trigonometry with log tables.
Doug