From: Douglas McIlroy <email@example.com> To: TUHS main list <firstname.lastname@example.org> Subject: [TUHS] RegExp decision for meta characters: Circumflex Date: Fri, 17 Sep 2021 12:40:43 -0400 [thread overview] Message-ID: <CAKH6PiUdxuOV3ySkD8m7W+O7k_Yh12XdtHnOkdAJFB4xfAiEig@mail.gmail.com> (raw) > Maybe there existed RE notations that were simply copied ... Ed was derived from Ken's earlier qed. Qed's descendant in Multics was described in a 1969 GE document: http://www.bitsavers.org/pdf/honeywell/multics/swenson/6906.multics-condensed-guide.pdf. Unfortunately it describes regular expressions only sketchily by example. However, alternation, symbolized by | with grouping by parentheses, was supported in qed, whereas alternation was omitted from ed. The GE document does not mention character classes; an example shows how to use alternation for the same purpose. Beginning-of-line is specified by a logical-negation symbol. In apparent contradiction, the v1 manual says the meanings of [ and ^ are the same in ed and (an unspecified version of) qed. My guess about the discrepancies is no better than yours. (I am amused by the title "condensed guide" for a manual in which each qed request gets a full page of explanation. It exemplifies how Unix split from Multics in matters of taste.) Doug
next reply other threads:[~2021-09-17 16:41 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-17 16:40 Douglas McIlroy [this message] 2021-09-17 20:40 ` Chris Torek 2021-09-18 1:03 ` Greg 'groggy' Lehey 2021-09-18 1:23 ` Bakul Shah -- strict thread matches above, loose matches on Subject: below -- 2021-09-17 8:52 markus schnalke 2021-09-17 9:32 ` Rob Pike 2021-09-17 9:32 ` Rob Pike 2021-09-17 10:10 ` markus schnalke
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