Re: Surprising behavior of eq?

[<tomas@tuxteam.de>]

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On Sun, Sep 20, 2020 at 05:37:45PM +0200, Zelphir Kaltstahl wrote:
> Hello John, hello Stefan!

[...]

> Of course SO is not a standard. Either it is simply wrong, or I
> misunderstood "primitive values" in that phrase. I thought: "Ah strings
> are a primitive value, so eqv? should work in all cases when comparing
> strings." However, this has been debunked.

Strings are mutable in Guile, so probably not what's called "primitive
values":

  scheme@(guile-user)> (define str (string-copy "the quick brown fox"))
  scheme@(guile-user)> (string-set! str 6 #\a)
  scheme@(guile-user)> str
  $3 = "the quack brown fox"

But string literals bark at you if you try to mutate them (that's why
I slyly created that one with `string-copy'):

  scheme@(guile-user)> (define str "the quick brown fox")
  scheme@(guile-user)> (string-set! str 6 #\a)
  ice-9/boot-9.scm:1669:16: In procedure raise-exception:
  string is read-only: "the quick brown fox"

Cheers
 - t

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