Condition

Condition(pattern, expr)

or

pattern /; expr

places an additional constraint on pattern that only allows it to match if expr evaluates to True.

Examples

The controlling expression of a Condition can use variables from the pattern:

>> f(3) /. f(x_) /; x>0 -> t
t

>> f(-3) /. f(x_) /; x>0 -> t
f(-3)

Condition can be used in an assignment:

>> f(x_) := p(x) /; x>0
>> f(3)
p(3)

>> f(-3)
f(-3)

Implementation status

• ✅ - full supported

Github

• Implementation of Condition