ligo/docs/language-basics-entrypoints.md

id	title
language-basics-entrypoints	Entrypoints

Defining an entry point

function main (const p : int ; const s : int) : (list(operation) * unit) is
  block {skip} with ((nil : list(operation)), s + 1)

Multiple entry points

Multiple entrypoints are currently not supported in Michelson, however with Ligo, you can work that around by using variants.

// variant defining pseudo multi-entrypoint actions
type action is
| Increment of int
| Decrement of int

function add (const a : int ; const b : int) : int is
    block { skip } with a + b

function subtract (const a : int ; const b : int) : int is
    block { skip } with a - b

// real entrypoint that re-routes the flow based on the action provided
function main (const p : action ; const s : int) : (list(operation) * int) is
  block {skip} with ((nil : list(operation)),
    case p of
    | Increment n -> add(s, n)
    | Decrement n -> subtract(s, n)
    end)