Isaac Schlueter wrote:
I see. So, you'd be suggesting using:
( args ) { functionBody }
as an anonymous function expression, though not a function expression
statement?
Right, see followup. The grammar without lookahead restrictions is
ambiguous. See ES5,
12.4 Expression Statement
Syntax
ExpressionStatement :
[lookahead ∉ {{, function}] Expression ;
NOTE An ExpressionStatement cannot start with an opening curly brace
because that might make it ambiguous with a Block. Also, an
ExpressionStatement cannot start with the function keyword because that
might make it ambiguous with a FunctionDeclaration.
Of course we cannot naively extend the lookahead rejection set to
include ( because that forbids a top level parenthesized expression
statement. One way around this is to refactor the grammar similarly to
what I propose in
http://wiki.ecmascript.org/doku.php?id=strawman:block_lambda_revival#syntax
to separate InitialValue from AssignmentExpression, and then allow
'function'-free function expressions as alternative right parts for
IniitalValues. Thus you could write such shorthand function expressions
in all places where you can write function expressions today, except
unparenthesized followed by . or [ or another operator (+ might be
useful, or confusing, sporadically).
This also allows us to extend the shorthand syntax to support an
expression body as well as a braced statement list:
IniitialValue:
AssignmentExpression
ShortFunctionExpression
AssignmentExpression:
...
LeftHandSideExpression = ShortFunctionExpression
ShortFunctionExpression:
Identifier_opt ( FormalParameterList_opt ) { FunctionBody }
Identifier_opt ( FormalParameterList_opt ) IniitialValue
without precedence inversion problems.
What about these?
;(( args ) { functionBody })
!( args ) { functionBody }
All fine, just as if you'd used the hated eight-letter keyword in front
of the (.
Certainly, this is quite nice:
myList.forEach((item) { .. })
Less nice for map because of the hated six-letter keyword, but yeah.
/be
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