"Write programs that produce and generate text, because that is a universal interface" is not a good principle for a compiler. (In fact, I think it's not really a good principle all around, and Unix is worse for it, but especially for a compiler.)

The author of the article is not writing a compiler.

I fail to see how that quote has any contextual connection with the current article or compiler design. A discussion about the merits of Unix text streams or text in general is another discussion entirely then the current one.

You yourself said "there is really no rigid boundary" between a compiler and a preprocessor. By most practical definitions of a compiler, the "C amplifier" discussed in the OP is a compiler, and is definitely similar enough to suffer many of the same issues as a compiler. In particular, I think what pcwalton is getting at is that in such a "pre-processor", it's likely that you'll eventually want more expressive data structures than text can comfortable offer you.

Can you given an example of how to write custom C abstractions with Awk?

[edit] keep in mind this is just a simple example. Awk is just one tool in the toolbox.

Take a look at 'The AWK Programming Language ' Alfred V. Aho, Brian W. Kernighan, Peter J. Weinberger.

http://www.amazon.com/The-AWK-Programming-Language-Alfred/dp...

Yes, its that Aho and Kerninghan...

operators to C function mapping. you can run like so.

$ awk -f fixed.awk < fixst.in > fixed.c

--- fixed.awk ---

  BEGIN {
  	printf("#include <stdio.h>\n");
  	printf("typedef long fixed;\n");
  	printf("void *send(fixed *this, char *message, ...);\n");
  }
  /^{/ { 
  	Ndecl = 0;
  	printf("{\n");
  }
  /^}/ { 
  	while(--Ndecl >= 0)
  		printf("\t%s\n", Destructor[Ndecl]);
  	printf("}\n");
  }
  /^:/ {
  	if($2~/fixed/) {
  		sub(/;/, "", $3);
  		printf("\tfixed *%s = send(NULL, \"fixed\");\n", $3);
  		Destructor[Ndecl++] = "send(" $3 ", \"~fixed\");"
  	}
  	else if ($4 ~ /(double)/) {
  		sub(/;/, "", $5);
  		printf("\tsend(%s, \"double\", &%s);\n", $5, $2);
  	}		
    	else if ($3 ~ /^=/) {
     		sub(/;/, "", $4);
    		printf("\tsend(%s, \"=\", %s);\n", $2, $4);
    	}
    	else if ($3 ~ /^\+/) {
    		sub(/;/, "", $4);
  		printf("\tsend(%s, \"+=\", %s);\n", $2, $4);
  	}
  	else if ($3 ~ /^\*/) {
  		sub(/;/, "", $4);
  		printf("\tsend(%s, \"*=\", %s);\n", $2, $4);
  	}
  }
  /^[^{}:]/ { print }

--- fixst.in ---

  int main()
  {
  :	fixed a;
  :	fixed b;
  :	fixed t0;
  :	fixed t1;
  	double f;
  :	a  = 1.00;
  :	b  = 9.99;
  :	t0 = 0.00;
  :	t1 = 2.00;
  :	t0 += t1;
  :	t0 *= b;
  :	t0 += a;
  :	f  = (double)t0;
  }