The strict Y fixed-point combinator. Allows for recursion of anonymous functions. Given a fn1 which contains a single named argument, and within which is an additional single-argument fn2, the innermost fn2 can call the named argument of fn1 as if it were a function name in order to recur on itself. For example, the factorial function can be defined thusly, using the Y-combinator:

Note however that usage of the Y-combinator for recursion is not especially efficient, and the more traditional recursive approach is generally recommended whenever possible (which is most of the time).

A generalization of the Y-combinator that allows the function to take any number of arguments.

Equivalent to (Y* (fn (name) (fn args body ...))). For example, to map the Fibonacci sequence without defining a named function to do it:

Returns a function with the args partially applied to fun, which can then be passed the remaining arguments, as many as needed to complete the calculation. For example:

Returns a new function which is a composition of fn1 and fn2. This function evaluates fn2 with its arguments, and then applies fn1 to the result of fn2.

Returns v.