Getting Started

Go from zero to your first Deft script in under five minutes.

Install Deft

Deft ships as a single binary. Download and put it on your PATH:

# Build from source (requires Zig 0.15+)

git clone https://github.com/deft-lang/deft-zig

cd deft-zig && zig build

# Verify installation

./zig-out/bin/deft_zig --version

Your first script

Use deft eval for quick one-liners, or create a .dft file:

# Quick evaluation

deft eval 'echo "Hello, Deft!"'

# => Hello, Deft!

# Math with grouping

deft eval '(2 + 3) * 4'

# => 20

Variables & Collections

Assign with set, reference with $. Deft has lists, maps, and sets built in:

# Variables
set name "Alice"
echo "Hi, $name!"

# Lists
set items @{ 1 2 3 4 5 }
[map $items {| x | ($x * 2)}]
# => @{ 2 4 6 8 10 }

# Maps
set config %{
   host "localhost"
   port 8080 }
    echo $config~host
# => localhost

Functions

Define functions with def. Parameters use type hints with ^:


def greet {| name^string |
    echo "Hello, $name!"
}

[greet "World"]
# => Hello, World!

# Multi-clause (dispatch on arity/type)

def area {| r^number | (3.14159 * $r * $r)}

def area {| w^number h^number | ($w * $h)}

Interactive REPL

Launch the interactive shell and experiment:

deft shell

# Now you're in the REPL -- try anything:

deft> set x @{ 10 20 30 }

deft> [reduce $x 0 {| a b | ($a + $b) }]

Build an HTTP server

Create app.dft and serve it:


def index {| req res |
    [html
         <h1>My Deft App</h1>
         <p>Hello from the Deft HTTP server! </p>
    \html]
}

def app %{
    routes @{
        %{ path "/" method :GET handler index }
    }
} |> [http/router]

deft serve http app.dft --port 3000

# Starting HTTP server on http://localhost:3000

Next steps

Shell Scripting

Core syntax, control flow, pipelines

{}

Types & Protocols

deftype, defprotocol, defimpl

Pattern Matching

match, destructuring, guards

Examples

One-liners and code examples