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Re: Can zsh `else` reserved keyword command be aliased and the lexem itself be repurposed as `fi` keyword command?

Hello Bart,

First, thank you for having taken some time to write this detailed answer.

Le 29/12/2017 à 09:38, Bart Schaefer a écrit :
If you haven't already, go read https://askubuntu.com/a/590335 which
was linked from

Your hypothetical "keyword" would have to itself be a keyword (and
thus not a command).
Yes, I had red it, and I even took time to read it again in case I missed something, but I didn't find what. Actually, it says "aliases can be used to alias keywords!", so it made me more confident about the fact that it might be possible.

I understand that the hypothetical "keyword" callable-stuff should be of type keyword however (however it's tricky to make clear sentences about such an intricated topic). I don't have in mind the whole interpretation pipeline in mind, an [acitivity diagram](http://plantuml.com/activity-diagram-beta) would be welcome here. However, it does  make  sense that the tool to make a substitution at some level must be at least at the same type level or in a type which is interpreted earlier.

What's the underlying reason for doing this?
Admitedly, it's an interesting challenge which enable to grab a little more knowledge on the shell.
  That is, aside from the
overall desire to write in Esperanto (?),  I get wanting "alie" to
mean the same thing "else" means, but not why "else" should mean "fi".
Because "else" could litteraly be translated "out of if". Maybe [12.3.2 Directional prepositions / Grammar - lernu.net](https://lernu.net/en/gramatiko/direktaj_prepozicioj) can give a good grab on this. And Esperanto is an agglutinate language, you can concatenate any set of lexemes and it will make sense (most of the time). And "el-" as a suffix is common place. But it's difficult to find resource in English to appreciate this, the online [plena ilustrita vortaro](http://vortaro.net/#el) does give an account of this practice – but in Esperanto.

Even in your "alie echo 'mirinda mondo'"  example it looks like "else"
is meant to act as "fi;else" so that you can continue with more of the
I'm not sure to understand what you mean here.

But for the sake of the example, you might consider a more complete "translation":

   alias se='enable -r else; if'
   alias alie='else'
   disable -r else
   alias else=":fi ; disable -r else"
   alias tiam='then'
   alias ja='['
   alias -g ope=']'
   alias -g plie='-a'
   alias -g vakua='-z'

   alias vera='true'
   alias eĥu='echo'

   se ja vakua $signvico plie vera ope nu tiam # [1]
        eĥu "la signvico estas vakua!"
        eĥu "la signvico ne estas vakua!"

[1] you might translate that as "if indeed $signvico (is) empty and furthermore (it's) true, all that together, well, then…".

In that peace of code, "alie" really is "else", or "otherwise" if you prefer.

This is doomed to failure, because complex shell syntax is fully
parsed before it is executed.  Your "disable" or "enable" has to take
place before the parsing step, because it won't be executed during the
parse.  Some extremely simple cases might appear to work at the
command prompt, but as soon as you embed them in a larger structure
like a function body they will fail.
Thus my demand in my other reply, is there a command that say to the shell, "ok, stop to eat the stream here and process the chunck of code you already buffered so far". As far as I understand, that's what a line break usually do. I tried to add one in the alias, including by using a heredoc string, but this doesn't work.
What is needed is an alias that ends recursive replacement.  Normally
one does this by including quoting (e.g., a leading backslash) in the
value of the alias, but that doesn't help in this case because it
prevents the replacement from being considered a keyword as well.
There may be a clever way to accomplish this -- recursion stops if
replacement results in a previously replaced alias, for example, to
avoid infinite loop -- but I haven't worked out an answer.
Well, I stay tune if anyone find any way to solve this challenging goal. ;)


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