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Cafe Fundamentals

This section covers fundamental concept of Structured Programming for any algorithm, that is Iteration, selection & Sub-sequence with the syntax to implement in cafe.

Comments#

Cafe supports single line comment using # Symbol and multi line comments using /*..*/

# this is a single line comment.
/*
this is a Multi-line comment.
*/

Variables & Constants#

As cafe is dynamically typed, the variables can be declared using var keyword and constants can be declared using const keyword.

var a=10, b;
const c = “Hey!”;

Data types#

String : represents sequence of characters.

Number: : represents numeric values.

Boolean : represents boolean value either true or false.

var a = “Hi”;
var b = 100, c=10.2;
var d=true;

Operators#

Symbol(s)DescriptionExamples
=Assign a value to a variable.var a = 10;
+Returns the sum of numeric operands or string concatenation.cmd.println(2+3); # 5 cmd.println(“Hello” + “World”); # HelloWorld
-Subtracts the two operands, producing their difference.cmd.println(4-2); # 2
*Multiplication on numbers and strings.cmd.println(4*2); # 8 cmd.println("Hello"*2) # HelloHello
/Division on numbers.cmd.println(4/2); # 2
%Modulo on numbers.cmd.println(8/3); # 2
**Computes the power of a number.cmd.println(2**3); # 8
//Computes the floor of a number.cmd.println(9//2); # 4
|| , && , !or , and, notLogical operators.cmd.println((true and true)); # true cmd.println(not true); # false
== , != , > , >= , <, <=Relational operators.cmd.println((2 >= 3)); # false
>> , >>> , ~ , <<Bitshift operators.cmd.println((2 >> 1)); # 1
& , | , ^ , ~Bitwise operators.cmd.println((2 & 2)); # 2

Control Flow#

if..else#

The if statement executes a statement if a specified condition is evaluated true.

If the condition is false, another statement can be executed.

Multiple if...else statements can be nested to create an else if clause.

Syntax

if(condition1)
Statement1
else if(condition2)
Statement2
...
...
else
StatementN

Example

var i=10;
if(i<10){
cmd.println(“Less Than 10”);
} else if(i==10){
cmd.println(“Equals”);
} else {
cmd.println(“Greater Than 10”);
}

for Loop#

The for statement creates a loop that consists of three optional expressions, enclosed in parentheses and separated by ;, followed by a statement (usually a block statement) to be executed in the loop.

Syntax

for ([initialization]; [condition]; [final-expression])
statements

Example

# prints 0 to 4.
for(var i=0;i<5;i=i+1){
cmd.println(i);
}
var i=0;
for(;i<5;i=i+1){
cmd.println(i);
}

{Object}#

Cafe Objects are a collection of properties made up of key-value pairs. Keys are unique & valid identifiers. Values can be any valid type (primitives, Functions or Objects). Objects can be declared using {} notation.

Syntax

{[[key: value],([key: value],)*]}

Example

var a = {};
func Hi(){ return “hi”; }
var a = {
hello: “world!”,
a: 1,
b: Hi # references a function object Hi.
};

Object properties can be accessed using the . or [] operator.

Syntax

object.property
object[property]

Example

var z = “a”;
cmd.println(a.hello); # world!
cmd.println(a.b()); # hi
cmd.println(a[“hello”]);# world!
cmd.println(a[z]); # 1

Function#

In CAFE, functions can be declared using keyword func.

Syntax

func name([param[, param,[..., param]]]) {
[statements]
}

name The function name.

param (Optional) The argument names to be passed to the function.

statements The statements which comprise the body of the function.

Example

func areaOfTriangle(base, height){
return 0.5 * base * height;
}
cmd.print(areaOfTriangle(5, 10)); # 25
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