FunL is a function-level language as defined by John Backus in his 1977 ACM Turing Award lecture, "Can Programming Be Liberated From the von Neumann Style?" Function-level languages are intended to "make programming sufficiently cheaper or more reliable to justify the cost of producing and learning to use them." (Backus 1977)

FunL can be best described by what it lacks:

• Variables
• Multiple scopes
• State

Because of this, it is very easy to take part of a FunL program and insert it into another FunL program without worry. FunL has an algebra of functions that allows for direct substitution of function definitions into function application, as well as comparing the equality of two functions.

All values in FunL are also functions, allowing the composition of any combination of values and functions in the language.

For a more full description, see http://github.com/cndreisbach/funl/blob/master/description.md.

length = map:1 | fold:+

length:[1, 2, 3] // => 3

// Decomposition of the above
// (map:1 | fold:+):[1, 2, 3]
// (fold:+):(map:1):[1, 2, 3]
// (fold:+):[1:1, 1:2, 1:3]
// (fold:+):[1, 1, 1]
// +:[+:[1, 1], 1]
// 3