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<<(+Number1, +Number2, -Result)
Shifts Number1 left by Number2 bits and unifies the
resulting value with Result.
- Output: integer.
This predicate is used by the ECLiPSe compiler to expand evaluable
arithmetic expressions. So the call to <<(Number1, Number2, Result) is
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
- (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.
Result is 1 << 3. % gives Result = 8
Result is 5 << 1. % gives Result = 10
Result is 10 << -1. % gives Result = 5
Result is -5 << 1. % gives Result = -10
Result is 1.1 << 3. % type error
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