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Append

Status: Stable

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

Description

Append[expr, elem] adds elem to the end of expr.

Examples (2)

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

Basic examples (2)

In[1]:= Append[<|"a" -> 1, "b" -> 2|>, "c" -> 3]
Out[1]= <|"a" -> 1, "b" -> 2, "c" -> 3|>

In[2]:= Append[<|"a" -> 1|>, "a" -> 99]
Out[2]= <|"a" -> 99|>

Implementation notes

builtin_append (in src/core.c) requires a 2-arg call Append[expr, elem] whose first argument is an EXPR_FUNCTION. It allocates a fresh argument array one slot longer than expr, deep-copies every existing argument plus elem into it, and rebuilds a new EXPR_FUNCTION with the same head. Works on any head, not just List. Returns NULL (unevaluated) when the first argument is atomic.

Attributes: none registered.

References

See also: Prepend, AssociateTo