Expression Structure

A foundational idea in the Wolfram Language is that all expressionswhatever they may representultimately have a uniform tree-like structure.

FullForm the full functional form of an expression, without shortened syntax

TreeForm a representation of the tree structure of small expressions

Head the head of an expression: the f in f[x,y]

Length the number of elements in an expression

Part (..[[..]]) numbered part of an expression

Level parts specified by a given number of indices

Depth the maximum number of indices to specify any part

Atomic Components of Expressions »

Symbol  ▪  Integer  ▪  Real  ▪  String  ▪  ...

Expression Sizes & Signatures

LeafCount  ▪  ByteCount  ▪  Hash

Expression Construction

Construct construct an expression from its head and arguments

Expression Enumeration

Groupings generate all possible expressions with particular structures