Expression types

Type	Description	Input Example
Integer	integer numbers	42
Rational	rational numbers	13/17
Complex	complex numbers	2+I*1/3
Real	double values	0.5
Complex Real	complex double values	0.5-I*0.25
Evaluation Precedence	control precedence with (...)	(a+b)*c
Lists	comma separated list of elements which are surrounded by { ... }	{a, b, c, d}
Vectors	vectors are like list, but cannot contain sub-lists { ... }	{1, 2, 3, 4}
Matrices	a matrix contains the rows as sub-lists	{{1, 2}, {3, 4}}
Sparse Arrays	sparse arrays are defined through their element positions	SparseArray({{1, 1} -> 1, {2, 2} -> 2, {3, 3} -> 3, {1, 3} -> 4})
Associations	comma separated list of rules which are surrounded by <| ... |> and create a dictionary or map	<|a->x, b->y, ...|>
Predefined Functions	predefined function names start with an upper case character and the arguments are enclosed by ( ... )	Sin(0), PrimeQ(13)
Predefined Constants	predefined constant names start with an upper case character	Degree, E, Pi, False, True, ...
User-defined variables	identifiers which you would like to assign a value start with a $ character in the server environment	$a=42
User-defined variables	in the Symja console app user-defined variables can be defined without a preceding $ character	a=42
User-defined rules	identifiers which you would like to assign a rule start with a $ character in the server environment	$f(x_,y_):={x,y}
User-defined rules	in the Symja console app user-defined rules can be defined without a preceding $ character	f(x_,y_):={x,y}
Pattern Symbols	patterns end with an appended _ character and could have a constraint	$f(x_Integer):={x}
Strings	character strings are enclosed by double quote characters	"Hello World"
Pure Functions	pure functions can be expressed with the & operator	(#^3)&[x] gives x^3
Slots	a # character followed by an optional integer number	# or #2
Slot Sequences	a # character followed by an optional integer number	## or ##2
Parts of an expression	expr[[index]]	{a, b, c, d}[[2]] gives b