The Kernel Programming Language
, by John N. Shutt:
Via Shriram Krishnamurthi on c.l.scheme. The story title is from an older paper on Kernel.
Kernel is a conservative, Scheme-like dialect of Lisp in which everything is a first-class object.
"But," you may ask, "aren't all objects first-class in Scheme?" (I'm glad you asked.) No, they aren't. Special-form combiners are second-class objects. To borrow a phrase from the original description of first- and second-class objects by Christopher Strachey, they have to appear in person under their own names. (There are also several other kinds of second-class objects in Scheme, but special-form combiners are the most commonplace.)
The idea of first-class operative combiners, i.e., first-class combiners whose operands are never evaluated, has been around a long time. Such creatures were supported by mainstream Lisps through the 1970s, notably under the name FEXPRs, but they made a mess out of the language semantics because they were non-orthogonal to the ordinary variety of procedures constructed via lambda.
Kernel eliminates the non-orthogonality problem by breaking the classical lambda constructor into two orthogonal parts, one of which is the Kernel constructor for first-class operatives.