3 Pattern Matching
3.1 Pattern Matching
Variables are bound to values through the pattern matching mechanism. Pattern matching occurs when evaluating a function call, case- receive- try- expressions and match operator (=) expressions.
In a pattern matching, a left-hand side pattern is matched against a right-hand side term. If the matching succeeds, any unbound variables in the pattern become bound. If the matching fails, a run-time error occurs.
Examples:
1> X. ** 1: variable 'X' is unbound ** 2> X = 2. 2 3> X + 1. 3 4> {X, Y} = {1, 2}. ** exception error: no match of right hand side value {1,2} 5> {X, Y} = {2, 3}. {2,3} 6> Y. 3