Syntax Cheat Sheet

Names used in examples

Concept	Ada
Reference	Access
Pointer	Access All
Namespace	P, Q, R
Class	Capricorn
Struct	Scorpio
Type	S, T, V, W
Variables	A, B, C
Function	Foo, Bar

Overview

Identifiers	Can't start with number or underscore, case insensitive
Keywords	Case insensitive, usually lower case
Naming Conventions(s)	Ada_Case(types and functions), keywords
Declaration file	FileName.ads
Definition file	FileName.adb
Dependency	with Package.Child;
Line comment	-- line comment
Block comment	N/A
Inline docs	Line comment before or after element

Program Structure

Compile-time config	N/A
Static assert	pragma Assert(cond);
	pragma Assert(cond, message);
Namespacing	package P
Child Namespaces	package P.R
Namespacing	package P
Namespace aliasing	package TIO renames Ada.Text_IO;
Using namespace	use Ada.Text_IO;
Using subprograms of type	use type T;
Scope resolution	P.Q.R
	private with Q;
	limited with P;
	private package P;
Ensuring module has no state	package P with Pure
No module initialization required	pragma Preelaborate(P);
Ensure elaboration immediately after specification	pragma Elaborate_Body;
Ensure other package is initialized before this one	pragma Elaborate(P);
Ensure other package and all dependencies are initialized before this one.	pragma Elaborate_All(P);
Prevent a dependency on another package	pragma Restrictions(No_Dependencies => Other_Package)

Memory

Pointer	Ptr : access all T;
Pointer to allocation from a specific pool	Ptr : access T;
Pointer deference	Ptr.all
Reference	Ptr : not null access T;
Variable used by Pointer	A: aliased T;
Address	Ptr : access T := T'Access(A)
Address	Ptr : access all T := T'Unchecked_Access(A)
Constant pointer	Ptr : constant access T;
Pointer to constant	Ptr : access constant T;
Constant pointer to constant	Ptr : constant access constant T
Prevents allocations to anonymous access types.	pragma Restrictions(No_Implicit_Heap_Allocation)
	pragma Restrictions(No_Anonymous_Allocators)
Dynamic allocation	A : access T := new T;

Special Notations

Equality	A = B
Inequality	A /= B
Assignment	A := B
Array Access	A(i)
Range	min .. max
"Box"	<>
Exponentiation	Base ** Exponent
Discrete type	(<>)
"Tick"	'
String Concatenation	A & B

Expressions

qualified expression	for all A of B => expr
qualified expression	for some A of B => expr
if expression	A : Boolean := (if A then B else C);
case expression	A : Integer = (case Value is when 0 => 1, when 1 => 1, when 2 .. 4 => 5, when 5 | 9 => 10, when others => 0);
Expression renaming	L2 : Float renames V.Length * V.Length;

Mathematics

Modify in-place	A := A + 1;
Modulus	mod
Remainder	rem
Exponentiation	A ** B
Bit shifting	In standard library

Control Flow

if	if A then statements; elsif B then statements; else statements; end if;
while	while A loop statements; end loop;
do-while	loop -- statements exit when A; end loop;
value-based loop	for Value in 0 .. 99 loop statements; end loop;
iterator-based loop	for Elem of Container loop statements; end loop;
Multiple choice	case Value is when 0 => Handle_Zero; when 1 => Handle_One; when 2 .. 4 => Handle_Range; when 7 | 9 => Handle_Choices; when others => Handle_Default; end case;
Iterate over enum	for Elem in EnumName loop statements; end loop;
Stop iterating	exit
Start exception handling	declare statements; exception when A => statements; when others => statements; end;
Empty statement (pass)	null;
Label	<<LABEL_NAME>>
goto	goto LABEL_NAME

Boolean Algebra

Equality	A = B
Inequality	A /= B
Not	not A
Boolean operators
or	A or B
and	A and B
Short circuiting boolean operators
or	A or else B
and	A and then B
Exclusive-Or (XOR)	A xor B
Implies (not A, or B)	(if A then B)

Functions and Procedures

Procedure	procedure Foo(X: in T; Y: in V) is begin statements; end Foo;
Function	function Fibonacci(X: Natural) return Natural is if X = 0 or X = 1 then return X; else return Fibonacci(X - 1) + Fibonacci(X - 2); end if; end Fibonacci;
Subprogram call (no parameters)	A;
Subprogram call with named Parameters	Foo(Bar1 => Value, Baz => Value2)
Override specifier	overriding procedure Foo(obj : in Object)
Ensure that a subprogram definition does not override an existing one	not overriding procedure Foo(obj : in Object)
Pass by pointer	procedure Foo (B : in access Bar)
Pass by reference	procedure Foo(B : in Bar)
Inline	procedure Foo with Inline
Using functions for a type unqualified.	use type P.Foo; -- Make primitive ops visible
	use all type P.Foo; -- Make all ops visible for type
Modifiable parameters	procedure Foo(B : in out Bar)
Expression function	function Foo return T is (expr)
Empty procedure	procedure Foo is null;

Types

Statically sized array	type Buffer is array(1 .. 128) of Integer;
Array Access	A(i)
Multi-dimensional Array	Mat4 : array (1 .. 4, 1 .. 4) of Float;
Built-In Variable length array	type Buffer is array(1 .. N) of Integer;
Semantic type	type Microseconds is new Integer;
Range checks on type	type My_Positive is range 1 .. 10;
Size	T'Size
Alignment	T'Alignment
Type Aliasing	subtype T is W;
Type parameterized by value (run-time)	type S(T: t) is record -- ...
Enum range	A'Range
Membership test	A in E
	A not in E
Type invariant checks	type T is new V with Type_Invariant => Expr(T)
Sum types	type S is (T, V, W);
Coercion (casting)	A := B(C);
Coercion with constraint check(casting)	A := B'(C);

Object-Oriented Programming

Class-like	type T is private;
Abstract class	type T is interface; function Foo(A : T) return V is abstract; procedure Bar(A: in out T) is abstract;
Subprogram call of object-like type	A.B;
Subprogram call of object-like type (alternative function-style form)	B (A);
Member access from pointer	A.all.B; -- Explicit
	A.B; -- Implicit
Prevent copying	type X is limited type;
Inheritance	type Foo is Bar with null record;
Dynamic dispatch (virtual function call)	procedure Foo(A : T'Class)
Prevent implicit cast	type T is new W;
Runtime type checking	if A in T then end if;
Passing parameter by base class	procedure Foo(A : BaseClass'Class)
Array-like indexing of user-defined type.	type My_Container is tagged type with Constant_Indexing =>Foo Variable_Indexing => Bar -- Foo and Bar are functions defined on the type.
Automatic dereference of a handle-type to the handle's contents.	type Handle(Target: not null access Element) is with Implicit_Dereference => Element; -- Old usage, calling Foo A_Handle.Target.all.Foo -- New usage A_Handle.Foo
Iterator for loops for user-defined types.	type My_Container with Default_Iterator => Iterate, Iterator_Element => Element_Type; type Cursor; function First (M : in My_Container) return Cursor; procedure Next (C : in out Cursor); function Has_Element (C : in Cursor) return Boolean;