Throw

Throw(value)

stops evaluation and returns value as the value of the nearest enclosing Catch. Catch(value, tag) is caught only by Catch(expr, form), where tag matches form.

Examples

Using Throw can affect the structure of what is returned by a function:

>> NestList(#^2 + 1 &, 1, 7)
{1,2,5,26,677,458330,210066388901,44127887745906175987802}

>> Catch(NestList(If(# > 1000, Throw(#), #^2 + 1) &, 1, 7))
458330

A Throw without an enclosing Catch prints the message: Uncaught Throw(1) returned to top level.

>> Throw[1]
Hold(Throw(1))

Implementation status

• ✅ - full supported

Github

• Implementation of Throw