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Nothing

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description

Nothing

is a symbol that is automatically removed from any list in which it appears as an element: {a, Nothing, b} evaluates to {a, b}. It is the identity element for list construction, so Table[If[test, val, Nothing], ...] builds a list of just the values for which test held. Any Nothing[...] form is removed likewise. Non-list heads treat Nothing as an ordinary symbol.

Examples (2)

Every input below was run against the current Mathilda build and its output recorded.

Basic examples (2)

In[1]:= {1, Nothing, 2}
Out[1]= {1, 2}

In[2]:= Table[If[EvenQ[i], i, Nothing], {i, 6}]
Out[2]= {2, 4, 6}

Implementation notes

Attributes: Protected.

References