gives expr with elem prepended.


represents an operator form of Prepend that can be applied to an expression.


  • Prepend works on SparseArray objects, returning ordinary lists if necessary.
  • Prepend can be used on Association objects. Single new elements are specified in the form key->value. New values replace older ones if their keys are the same.
  • Multiple elements to prepend to an association can be specified in the form {key1->value1,key2->value2, }.
  • Prepend[elem][expr] is equivalent to Prepend[expr,elem].


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Basic Examples  (3)

Prepend to an Association:

Prepend several rules to an Association:

Generalizations & Extensions  (1)

Use a head other than List:

Applications  (4)

Prepend a row to a matrix:

Prepend to each row in a matrix:

Prepend a vector to a matrix:

Successively prepend to a list:

Possible Issues  (1)

Introduced in 1988
Updated in 2003