Functionals & Operators Video Version

Many built-in functions in the Wolfram Language can use "functional" or "operator" forms.

This gives the element of a list nearest to 6.3:

In[1]:=1

Nearest[{1, 4, 6, 8, 10, 15}, 6.3]

Out[1]=1

This sets up a "nearest function," ready to apply to any specific value:

In[2]:=2

Nearest[{1, 4, 6, 8, 10, 15}]

Out[2]=2

Applying it to a particular value gives a specific result:

In[3]:=3

%[6.3]

Out[3]=3

Notes for Java programmers:

Java methods do not typically have "operator" forms.

Notes for Python programmers:

The "operator" forms in the Wolfram Language enable the creation of new functions by providing some of the arguments of a built-in function. Similar functionality in Python would require calling the partial function or writing your own custom wrapper function.

With no explicit data supplied, this symbolically represents a selection operation:

In[1]:=1