Re: Pointers to "why C behaves like that ?"

On 24 Nov 2002 thp@cs.ucr.edu wrote:
>
> There is still the argument that a typo might create a new variable
> instead of a syntax error, e.g.:
>
[examples snipped]
>
> the typo will produce an unused-variable warning.


Yes. In fact, I've bootstrapped my own simple language (C-like,
untyped, 16-bit, medium-level) which contains no keywords for data
types at all, and thus no declaration syntax. To guard against typos,
I say that if we see


      hellowrold;


that is a "declaration", not an error; and if we see


      hellowrold = 42;


that is an "initialization", not an error; but if we see


      printf(hellowrold);
or
      helloworld = hellowrold;


they are most likely errors and cause compile-time warnings when a
certain DEBUG flag is set (which it is, by default).


> To insure against such repeated typos, the language can require a
> keyword to accompany the introduction of a new variable, e.g.:
>
> let profit = income - expenditures;
>
> In such a case the first typo above would produce a syntax error.


In fact, instead of "let", why don't we use "var" to indicate a new
VARiable, or "my", to indicate that the variable is MY program's?
For example,


      my $programs
      use perl;


We could even go further to insure against more insidious logic errors
by specializing; say,


      let int profit = income - expenditures;
      let float cost = labor - price;


Then we could even lose the "let", and just use "int" and "float" to
represent the "let" keyword!


Hmm... sounds familiar, don't it?
:-)


-Arthur

Return to the comp.compilers page.
Search the comp.compilers archives again.