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<<(+Number1, +Number2, -Result)
Shifts Number1 left by Number2 bits and unifies the
resulting value with Result.
- Number1
- Integer.
- Number2
- Integer.
- Result
- A variable or integer.
Description
   This predicate is used by the ECLiPSe compiler to expand evaluable
   arithmetic expressions.  So the call to <<(Number1, Number2, Result) is
   equivalent to
    Result is Number1 << Number2
    which should be preferred for portability.
   The shift behaves as if operating on an unlimited length two's complement
   representation.  Shifting by a negative amount is the same as shifting by
   the same positive amount in the other direction.
   In coroutining mode, if Number1 or Number2 are uninstantiated, the call
   to <</3 is delayed until these variables are instantiated.
Modes and Determinism
Exceptions
- (4) instantiation fault 
- Number1 or Number2 is not instantiated (non-coroutining mode    only).
- (5) type error 
- Number1 or Number2 is a number but not an integer.
- (24) number expected 
- Number1 or Number2 is not of a numeric type.
Examples
Success:
      <<(1, 3, 8).
Fail:
      <<(1, 2, 3).
      <<(6, 2.0, 24.0).
      <<(5, 2, r).
Error:
      <<(A, 2, 6).              (Error 4).
      <<(4 + 2, 2, 24).         (Error 24).
See Also
is / 2