It seems ∀ (\forall) is not allowed for some reason: julia> const ∀ = for ERROR: syntax: invalid character "∀" near column 7 Why is that? Is it just because it’s not on one of the character lists in the parser source code?

https://github.com/JuliaLang/julia/issues/19012

But the character is still “disallowed”. What prevents it from being available? I don’t want any special syntax parsing for it, just to be allowed for general use. You can break pretty much anything, so it’s not a 100% sound reason: julia> const + = - - (generic function with 192 methods) julia> …

[image] anon37204545: You can break pretty much anything Yea but we will not redefine + to - in Julia base. If ∀ was allowed in e.g. variable names, then code like a∀b = 1 would break if we decide we want to introduce ∀ as an operator.

Incidentally, const <...anything...> = for will not work as for is a keyword and the parser will expect the relevant forms after it.

[image] Tamas_Papp: will not work as for is a keyword This is specially important. You are trying to use a const variable as it was a C macro, you want that any reference to that token/name is replaced by the code in the right-hand side in any context. This would never work. You can use a mac…

You need to use string macros here or a special repl mode if you want this syntax. using ReplMaker using REPL: LineEdit iscomplete(x) = true function iscomplete(ex::Expr) if ex.head == :incomplete false else true end end function valid_code(s) input = String(take!(…

Why ∀ is an invalid character?

Internals & Design

StefanKarpinski August 22, 2020, 4:26pm 3

TLDR so that we can decide how they should work without breaking anything.

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Why ∀ is an invalid character?

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