Re: ¿Error in the reference manual?

[Roberto Ierusalimschy <roberto@...>]

> Hello,
> 
> If I understand it properly, according to the grammar at the end of
> the reference manual,
> the following statement should be legal (although it isn't in practice):
> 
> a = function() break end
> 
> http://www.lua.org/manual/5.1/manual.html#8
> 
> Here are the relevant entries:
> 
> 	function ::= `function´ funcbody
> 	funcbody ::= `(´ [parlist] `)´ block `end´
> 	block    ::= chunk
> 	chunk    ::= {stat [`;´]} [laststat [`;´]]
> 	laststat ::= `return´ [explist] | `break´
> 
> I'm a self thought programmer, so my grasp of theoretical CS is a bit
> hazy. Does the bug lie in the spec or in my mind?

Breaks can only appear inside loops. This is a "semantic restriction",
because it is too complicated to express this restriction in the
grammar. (A similar restriction is that the expression '...' can only be
used in vararg functions.)

-- Roberto