Parts of the Showcase API rely on the usage of lambda expressions for call-backs. A lambda expression is a kind of function which has no name, also called an anonymous function. It can be assigned to a variable, or passed to a function. Lambda expressions can refer to variables in their surrounding context (i.e. scope).
The following is a simple example of a lambda-expression assigned to a variable:
>>> inc = lambda x: return x + 1 >>> print inc(41) 42
The following is an example of a lambda-expression passed as an argument to a function:
>>> xs = [2, 3, 4, 5, 6, 7] >>> print filter(lambda x: x % 2 == 0, xs) [2, 4, 6]