Catch

Catch(expr)

returns the value argument of the first Throw(value) generated in the evaluation of expr.

Catch(expr, form)

returns value from the first Throw(value, tag) for which form matches tag.

Catch(expr, form, f)

returns f(value, tag).

Examples

Exit to the enclosing Catch as soon as Throw is evaluated:

>> Catch(r; s; Throw(t); u; v)
t

Define a function that can “throw an exception”:

>> f(x_) := If(x > 12, Throw(overflow), x!)

The result of Catch is just what is thrown by Throw:

>> Catch(f(1) + f(15))
overflow

>> Catch(f(1) + f(4))
25

Implementation status

• ✅ - full supported

Github

• Implementation of Catch