Getting Started

This page walks you from a fresh machine to a working multi-function ilo program. For install options on every platform, see Install.

Install

The fastest path on macOS or Linux:

Shell

curl -fsSL https://raw.githubusercontent.com/ilo-lang/ilo/main/install.sh | sh

Verify it works:

Shell

ilo 'dbl x:n>n;*x 2' 5
# 10

If you use Claude Code, run /plugin marketplace add ilo-lang/ilo then /plugin install ilo-lang/ilo and your agent picks up ilo automatically. See Install for npm, Windows, source builds, and other agents.

Your first program

Create hello.ilo:

ilo

greet name:t > t
  +"hello " name

Run it:

Shell

ilo hello.ilo greet "world"
# hello world

That’s a complete ilo program. Here is what each part means:

Part	Meaning
greet	function name
name:t	parameter name, type text
> t	returns text
+"hello " name	body: concatenate two strings (prefix +)

Now try numbers. Create math.ilo:

ilo

add a:n b:n > n  -- n = number, t = text
  + a b          -- prefix: + a b means a + b

Shell

ilo math.ilo add 3 4
# 7

Inline mode

You can also run ilo without a file. Semicolons replace newlines and indentation:

Shell

ilo 'add a:n b:n>n;+a b' 3 4
# 7

This is the form AI agents use, same language, just compressed to one line. See the CLI Reference for more.

Multiple functions

ilo programs can contain multiple functions. Each function is a named declaration separated by a newline (in files) or a space (inline):

Save this as math.ilo:

ilo

dbl x:n>n;*x 2
inc x:n>n;+x 1
sq x:n>n;*x x

Selecting a function from the CLI

When a program has multiple functions, name the one you want to run after the filename:

Shell

ilo math.ilo dbl 5
# 10

ilo math.ilo sq 5
# 25

If you omit the function name, ilo runs the first one:

Shell

ilo math.ilo 5
# 10  (runs dbl, the first function)

Inline programs work the same way:

Shell

ilo 'dbl x:n>n;*x 2 sq x:n>n;*x x' dbl 5
# 10

ilo 'dbl x:n>n;*x 2 sq x:n>n;*x x' sq 5
# 25

Functions can call each other

Functions in the same program can reference each other:

ilo

dbl x:n > n        -- double a number
  *x 2             -- multiply x by 2

quad x:n > n       -- quadruple a number
  dbl(dbl x)       -- double x, then double again

Shell

ilo 'dbl x:n>n;*x 2 quad x:n>n;dbl(dbl x)' quad 3
# 12

For splitting functions across files, see Imports.

Where to next

• Manifesto for the why
• Real-World Examples for end-to-end programs
• Reference for the full language spec
• Builtins for the stdlib