/****************
Compiling this program gives:
[sqr-bug02.diderot:22.32-38] Error: undeclared variable 'foobar'
uncaught exception Fail [Fail: Error in compiling sqr-bug02.diderot]
  raised at common/phase-timer.sml:76.50-76.52
  raised at common/phase-timer.sml:76.50-76.52
  raised at driver/main.sml:27.39-27.76

So there is both the "Error" and the "Fail".
When there is a descriptive Error message, why have
all the uncaught exception stuff?

****************/

real eps = 1.0;
strand sqroot(real val) {
   output real root = val;
   update {
      root = (root + val/root)/2;
      if (|root^2 - val|/val < foobar)
         stabilize;
   }
}
// Strand initialization
initially { sqroot(i) | i in 1..1000 };