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Quick Start

This guide will walk you through creating and running your first Dryft program.

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Your First Program: Hello World

Let’s start with the classic “Hello, World!” example.
1

Create a new file

Create a file named hello.dry:
touch hello.dry
2

Write the code

Open hello.dry and add the following:
hello.dry
include: std/io

act: main
    "Hello, World!\n" prints ;
Let’s break this down:
  • include: std/io - Imports the standard I/O library
  • act: main - Defines the main action (entry point)
  • "Hello, World!\n" prints - Pushes a string to the stack and prints it
  • ; - Ends the action definition
3

Compile the program

Compile using the default GCC backend:
dryftc hello.dry
This will:
  1. Compile hello.dry to C code (build/ir.c)
  2. Compile the standard library
  3. Assemble the C code to an object file
  4. Link everything into an executable (a.out)
4

Run the executable

Execute your program:
./a.out
Output:
Hello, World!
You can compile and run in one step using the -r flag:
dryftc hello.dry -r

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Understanding the Stack

Dryft is a stack-based language. Values are pushed onto a stack and operations consume them: 
# Push 3 and 4 onto the stack, then add them
3 4 +        # Stack: [7]

# Push another value and multiply
2 *          # Stack: [14]

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Example: Simple Arithmetic

Create math_example.dry: 
include: std/io

act: main
    # Solve: (6/2)(1+2)
    "(6/2)(1+2) = " prints
    6 2 / 1 2 + * printi
    "\n" prints
    
    # Solve: 6/(2(1+2))
    "6/(2(1+2)) = " prints
    6 2 1 + 2 * / printi
    "\n" prints
;
Compile and run: 
dryftc math_example.dry -r
Output: 
(6/2)(1+2) = 9
6/(2(1+2)) = 1
No operator precedence rules needed! Operations are evaluated left-to-right as they appear.

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Variables and Functions

Dryft supports variables and function definitions: 
include: std/io

# Pure function: doubles a number
fun: double
    copy + ;

# Pure function: increments a number
fun: inc
    1 + ;

act: main
    # Store value in variable
    5 var: x
    
    # Use the variable
    $x double printi "\n" prints
    
    # Update the variable
    $x inc x!
    $x printi "\n" prints
;

5 var: x          # Declare and initialize x with 5
$x                # Read variable x (pushes value to stack)
10 x!             # Update x with new value (10)

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Control Flow Example

Let’s create a simple counting program using loops and conditionals: 
include: std/io

act: main
    10 var: max
    0 var: i
    
    cycle:
        $i $max =? then break ;
        $i printi " " prints
        $i 1 + i!
    :cycle
    
    "\n" prints
;
Compile and run: 
dryftc count.dry -r
Output: 
0 1 2 3 4 5 6 7 8 9

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Complete Example: Factorial Calculator

Here’s a more advanced example showing pure functions with variables and loops: 
include: std/io

# Calculate n!
fun: factorial var: n
    1 var: result
    cycle: $n 0 =? then break ;
        $result $n * result!
        $n 1 - n!
    :cycle
    $result
:fun

act: main
    "10! = " prints
    10 factorial printi
    "\n" prints
;
Output: 
10! = 3628800

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Compiler Options

The dryftc compiler supports several useful options: 
# Compile with default target (GCC)
dryftc program.dry

# Compile and run
dryftc program.dry -r

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Interactive REPL

Dryft includes a REPL (Read-Eval-Print Loop) for interactive development: 
dryftc
Example REPL session: 
Dryft repl> 3 4 + printi
7
Dryft repl> 5 var: x
Dryft repl> $x 10 * printi
50
Dryft repl> .help
.help/help  => display this screen
.exit/.quit => leave the REPL, terminating this process
.view       => inspect the contents of generated IR from last execution
Dryft repl> .exit
The x86 backend is not stable in the REPL environment. Use the default GCC backend for REPL sessions.

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Example Programs

Explore the examples/ directory for more complex programs:

hello.dry

Simple “Hello, World!” program

fizzbuzz.dry

Classic FizzBuzz with conditionals and loops

math.dry

Mathematical functions: factorial and exponentiation

example.dry

Comprehensive feature showcase

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Next Steps

Now that you can write and compile Dryft programs, dive deeper into the language:

Language Guide

Learn Dryft’s syntax, types, and features in detail

Standard Library

Explore available standard library functions

Examples

Study complete example programs

Type System

Understand Dryft’s linear type system

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Common Patterns

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Printing Values

42 printi              # Print integer
"Hello" prints         # Print string
"\n" prints            # Print newline

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Stack Manipulation

copy                   # Duplicate top of stack
swap                   # Swap top two values

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Comparisons

5 5 =?                 # Equal? Returns bool
5 3 >?                 # Greater than?
5 3 <?                 # Less than?
5 5 >=?                # Greater than or equal?

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Conditionals

# Simple conditional
true then: "yes" prints ;

# If-else with when
when:
    condition then: "yes" ;
    "no" ;
prints
You’re now ready to start building with Dryft!

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