Closures

Closures are formed with the following syntax: [ arg -> | (arg1, arg2, ...) -> ] { body }. A closure without an argument list automatically has the signature (self, *argnames, **kwargnames).

Example 1

BuildDSLPython

filter({ self % 2 }, range(5))

def _closure_1(self, *argnames, **kwargnames):
    self % 2
filter(_closure_1, range(5))

No return statement

Note how a closure surrounded by braces does not have an implicit return statement.

Example 2

BuildDSLPython

filter(x -> x % 2, range(5))

def _closure_1(x):
    return x % 2
filter(_closure_1, range(5))

Example 3

BuildDSLPython

reduce((a, b) -> {
  a.append(b * 2)
  return a
}, [1, 2, 3], [])

def _closure_1(a, b):
    a.append(b * 2)
    return a
reduce(_closure_1, [1, 2, 3], [])