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From: Bart Schaefer <schaefer@brasslantern.com>
Message-Id: <151021114653.ZM2741@torch.brasslantern.com>
Date: Wed, 21 Oct 2015 11:46:53 -0700
In-Reply-To: <5627D2F8.3000004@eastlink.ca>
Comments: In reply to Ray Andrews <rayandrews@eastlink.ca>
        "Re: suprise with -=" (Oct 21, 11:01am)
References: <562483C9.1060602@eastlink.ca> 
	<151019113517.ZM32739@torch.brasslantern.com> 
	<562545DD.5020008@eastlink.ca> 
	<151019172744.ZM558@torch.brasslantern.com> 
	<5627D2F8.3000004@eastlink.ca>
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Subject: Re: suprise with -=
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On Oct 21, 11:01am, Ray Andrews wrote:
} Subject: Re: suprise with -=
}
} On 10/19/2015 05:27 PM, Bart Schaefer wrote:
} > The parser doesn't know that "first" is an integer, or even that it's
} > a variable that was previously declared.
} That puzzles me.  Have not all your examples demonstrated that the 
} parser is aware of the type of the variable and that it will perform 
} it's operations accordingly?

No.  Parser is syntax, not semantics.  It knows "x=y" has a valid shape,
and to create code to invoke an assignment at run time, but not what the
assignment will do with x or y when run.

You can think of "third=first+second" as syntactic sugar for the command
"typeset third=first+second" -- it's the command that knows the type of
the variable, not the parser.