elves / upgrade-scripts-for-0.17 Goto Github PK

Long ago, when I first started using Elvish, I wrote a nx function. Its purpose is to run an external command and ignore specific non-zero exit status exceptions. The function employs the local: namespace prefix. This statement:

local:exc = $ok

Was mutated to this:

var local:exc = $ok

Which results in this error when starting a new Elvish shell:

Exception: compilation error: variable declared in var must be unqualified
/Users/krader/.config/elvish/lib/util.elv, line 104:     var local:exc = $ok
/Users/krader/.config/elvish/rc.elv, line 37: use util

I ran upgrade-scripts-for-0.17 -w **.elv in my ~/.config/elvish directory. It reported a bunch of errors like this one:

Multiple parse errors:
  should be variable name
    [stdin], line 174:
      	&su= $&segment_su

It wasn't hard to find the offending script but it would be nice if the error message reported the pathname rather than [stdin]. In this case the error(s) were due to lib/github.com/muesli/elvish-libs/theme/muesli.elv that I installed long, long, ago but never used after trying it once. It might also be better to simply stop after the first parse error since a parse error means that any further effort to convert the script is unlikely to yield useful results and likely to result in a lot of additional parse errors.

This is just a FYI. I do not actually expect any changes to accommodate this scenario. I accidentally ran this tool twice in a row using the latest version of the tool as I write this:

upgrade-scripts-for-0.17 -lambda -w **[type:regular].elv

That resulted in a sequence of errors like this:

Multiple parse errors:
  should be '}'
    lib/interactive.elv, line 31:
      fn hr {||]
  unexpected rune ']'
    lib/interactive.elv, line 31:
      fn hr {||]

Which is not at all surprising yet still surprised me. It made we ponder whether it is possible to do better by only converting a file once? The obvious approach is to add a prefix, such as "# elvish 0.17.0\n", to the transformed output. The presence of that prefix causes the conversion tool to ignore the file. That, however, is a fragile mechanism with ambiguities. I don't expect this to be resolved but wanted to document the problem in case there was an obvious (other than to me) solution.

Minmal example:

⬥ echo 'x = []{ nop }' | upgrade-scripts-for-0.17 -lambda
var x = {||] nop }

I have no idea why one of my scripts used this construct, but it did. It's an odd corner case that nevertheless should be fixed.

Edited to add: No problem with [ ]{ nop }. A single space makes all the difference.