I don’t think think this is a bug in j and don’t think it is an easy fix.
Probably better things to work on.

On Tuesday, March 22, 2022, bill lam <[email protected]> wrote:

> This is a bug in J.  J should follow MacOS file system name normalization
> rule. I'll take a look.
>
>
> On Wed, 23 Mar 2022 at 11:01 AM Eric Iverson <[email protected]>
> wrote:
>
> > Not sure. And not sure I want to know.
> >
> > But to continue the example:
> >    fread c NB. fails on macos as the system has the decomposed form as
> the
> > name it looks for
> >    fread d
> > abc
> >
> >
> > On Tue, Mar 22, 2022 at 9:39 PM Elijah Stone <[email protected]>
> wrote:
> >
> > > I wonder what happens when you create two files with distinct names,
> and
> > > then unicode changes such that they are the same when
> > > normalised/casefolded/..
> > >
> > > Probably nothing good.
> > >
> > > On Tue, 22 Mar 2022, Eric Iverson wrote:
> > >
> > > > My favorite unicode story is from macos filenames.
> > > >
> > > > They decompose filenames and only track the decomposed form (letter
> > > > separate from the overstrike).
> > > >
> > > > The following accented chars look the same, but have different
> values.
> > > >
> > > >   c=: 195 164{a. NB. composed
> > > >   c
> > > > ä
> > > >   d=: 97 204 136{a. NB. decomposed
> > > >   d
> > > > ä
> > > >   c-:d
> > > > 0
> > > >   'abc'fwrite c
> > > >   fread c NB. fails on macos as the system has the decomposed form as
> > the
> > > > name it looks for
> > > >
> > > > Torvald has a wonderful rant about this that is a fun read.
> > > >
> > > > On Tue, Mar 22, 2022 at 7:02 PM Raul Miller <[email protected]>
> > > wrote:
> > > >
> > > >> I ran into a situation, today (dealing with files), where most of
> the
> > > >> files were utf-8 encoded but some represented the latin-1 "code
> plane"
> > > >> with 8 bit characters.
> > > >>
> > > >> To cope with this issue, I coded up a mechanism to test whether the
> > > >> file contained only valid utf-8 sequences, and used {{ ": 10 u: y }}
> > > >> for the files which failed this test.
> > > >>
> > > >> In other words:
> > > >>
> > > >> cclass=: (i.9) (48+i.9)} 256#9
> > > >> cstates=: 0 10#:10* ".;._2{{)n
> > > >>   0    7.3  2    3    4    5    6    7.3  7.3  7.1 NB. 0: start char
> > > >> sequence
> > > >>   0    7.3  2    3    4    5    6    7.3  7.3  7.1 NB. 1: finish
> char
> > > >> sequence, start next
> > > >>   7.3  1    7.3  7.3  7.3  7.3  7.3  7.3  7.3  7.3 NB. 2: need one
> > > >> more character
> > > >>   7.3  2    7.3  7.3  7.3  7.3  7.3  7.3  7.3  7.3 NB. 3: need two
> > > >> more characters
> > > >>   7.3  3    7.3  7.3  7.3  7.3  7.3  7.3  7.3  7.3 NB. 4: need three
> > > >> more characters
> > > >>   7.3  4    7.3  7.3  7.3  7.3  7.3  7.3  7.3  7.3 NB. 5: need four
> > > >> more characters
> > > >>   7.3  5    7.3  7.3  7.3  7.3  7.3  7.3  7.3  7.3 NB. 6: need five
> > > >> more characters
> > > >>   7.3  7.3  7.3  7.3  7.3  7.3  7.3  7.3  7.3  7.2 NB. 7: end
> > > >> }}
> > > >>
> > > >> utf8lenb=: <:2#.>1 #each~1+i.8
> > > >> utf8ok=: {{
> > > >>   try.
> > > >>     (1;cstates;cclass) ;: '.',~'012345678_'{~ utf8lenb I. 3 u: y
> > > >>     1
> > > >>   catch.
> > > >>     0
> > > >>   end.
> > > >> }}
> > > >>
> > > >> NB. most content is utf-8 -- assume non-utf-8 sequences are
> > > ascii+latin-1
> > > >> latin2utf8=: {{
> > > >>   if.utf8ok y do. y else. ":10 u: y end.
> > > >> }}
> > > >>
> > > >> I don't know if this approach would be useful to anyone else here,
> > > >> but... just in case...
> > > >>
> > > >> FYI,
> > > >>
> > > >> --
> > > >> Raul
> > > >> ------------------------------------------------------------
> ----------
> > > >> For information about J forums see
> > http://www.jsoftware.com/forums.htm
> > > >>
> > > > ------------------------------------------------------------
> ----------
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> forums.htm
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> >
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