exception
Exceptions signalling unification failures.
tuprolog.unify's functions and unificators report failures as values (the failed substitution,
None, or False): these exceptions are raised by the code needing two terms to unify, and are
tuprolog.errors.UnificationErrors (hence ValueErrors).
module-attribute
¶
NoUnifyException = _exceptions.NoUnifyException
Two terms could not be unified.
Constructed as NoUnifyException(term1, term2); its message names the two terms. It is a
tuprolog.errors.UnificationError, hence a ValueError.
Examples:
>>> from tuprolog.core import atom
>>> NoUnifyException(atom("a"), atom("b")).message
'Cannot match term `a` with term `b`'
module-attribute
¶
OccurCheckException = _exceptions.OccurCheckException
Two terms could not be unified because of the occurs check.
A NoUnifyException whose cause is a variable occurring in the term it should be bound to (e.g.
X and f(X)). Constructed as OccurCheckException(term1, term2, variable, term).