function: naming a reusable job
function add(a, b):
return a + b
say add(2, 3)
Parameters are comma-separated identifiers. Empty parameter lists and trailing
commas are allowed. See Section 11 for function semantics.
Declaration and call
# language: en
function factorial(number):
if number <= 1:
return 1
return number * factorial(number - 1)
say factorial(5)
Functions have a fixed number of positional parameters. User-function arity is
checked when the callee can be resolved statically and again at runtime for a
dynamic call.
Pliro currently has no default, named, optional, variadic, typed, or destructured
parameters.
Arguments are passed as values. Lists and maps retain the collection-sharing
behavior described in Section 9.6, so a function can
update an existing element of a collection supplied by its caller.
Return value
return expression returns a value. Bare return and function fallthrough
return none:
function announce(message):
say message
return
Closures and nested functions
User functions close over their lexical environment:
# language: en
function makeCounter(start):
let value = start
function next():
set value = value + 1
return value
return next
let counter = makeCounter(10)
say counter()
say counter()
Functions are first-class runtime values: they can be stored, passed, returned,
and called. There is no anonymous-function or lambda syntax.
Recursion limits
Direct recursion is supported. Runtimes enforce a bounded maximum user-function
call depth and produce a structured runtime error instead of overflowing the
host stack. Session runtimes make this bound configurable; the current generated
native runtime fixes it at 256.