Improve on library imports

[DartBot]

This issue was originally filed by carstenkl...@yahoo.de

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In the specs it reads

libraryImport:
'#' 'import' '(' stringLiteral (', ' 'prefix:' stringLiteral)? ') ';'
;

This is utterly redundant.

I would like to suggest that this will be reduced to either

libraryImport:
'#' 'import' stringLiteral 'as' stringLiteral;
;

or, by making this more 'compatible' to CommonJS

libraryImport:
stringLiteral = 'import' stringLiteral;
;

The extra opening and closing brackets are not really necessary unless

import was a function, which it definitely is not.

And if it were, then the '#' hash before the 'import' keyword should be removed, leaving us with

libraryImport:
stringLiteral = 'import' '(' stringLiteral ')';
;

Having this, one could also just import specific elements declared by the library, such as

foo = import('bar').foo;

or, using the import...as notation

libraryImport:
'import' '(' stringLiteral ')' ('as' stringLiteral)?;
;

However, using stringLiteral for the prefix is rather weak, as it definitely needs to be an identifier.

[DartBot]

This comment was originally written by drfibonacci@google.com

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Added Area-Language, Triaged labels.

[DartBot]

This comment was originally written by carstenkl...@yahoo.de

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Well, having read through the specification once more, I find that most of what is stated above can just be ignored.

The only thing left you might take into consideration when finalizing the specification is that the prefix must be an identifier since it is also to be used as a namespace. And since stringLiteralS normally include all strings, even those with whitespace, it is IMO mandatory that the prefix is a valid identifier of the language.

[gbracha]

The next rev of the spec will state that the prefix string must evaluate to a string that is a valid identifier. Good catch.

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Set owner to @gbracha.
Added Done label.