PS-algol

! PS-algol factorial calculator with persistence
let factorial = proc(int n -> int)
    if n <= 1 then 1 else n * factorial(n - 1)

let main = proc()
begin
    let db = open.database("factorials")
    let n := read.int()

    ! Check if result is already in database
    let key = "fact_" ++ n.to.string()
    let result :=
        if db.has(key) then
            db.lookup(key)
        else
        begin
            let value = factorial(n)
            db.insert(key, value)
            value
        end

    write "Factorial of ", n, " is ", result
    close.database(db)
end

main()