Further Examples: Fold

Here is a definition of the factorial function in functional programming style.

In[1]:=

In[2]:=

Out[2]=

Here is an implementation of Horner's rule.

In[3]:=

Out[3]=

Here Fold is used to give the alternating sum of a list.

In[4]:=

In[5]:=

Out[5]=

Union with one argument drops duplicates from a list and reorders the remaining elements.

In[6]:=

Out[6]=

Here is a function that also drops duplicates from a list but does not reorder the remaining elements. (See the Further Examples for Union for a version which is considerably faster on long lists with many distinct elements.)

In[7]:=

In[8]:=

Out[8]=

In[9]:=

(See the Further Examples for ReplacePart for a powerful application of Fold to partial evaluation of held expressions.)