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].
Introduced in 1988
| Updated in 2014