2.15.4 Specification

The formal syntax of a specialized expression, in the style of the Revised^5 Report on the Algorithmic Language Scheme:

<cut-expression> -->  (cut  <slot-or-expr> <slot-or-expr>*)
                    | (cut  <slot-or-expr> <slot-or-expr>* <...>)
                    | (cute <slot-or-expr> <slot-or-expr>*)
                    | (cute <slot-or-expr> <slot-or-expr>* <...>)

<slot-or-expr>   -->  <>              ; a "slot"
                    | <expression>    ; a "non-slot expression"

The macro cut transforms a <cut-expression> into a <lambda expression> with as many formal variables as there are slots in the list <slot-or-expr>*. The body of the resulting <lambda expression> calls the first <slot-or-expr> with arguments from <slot-or-expr>* in the order they appear.

In case there is a rest–slot symbol, the resulting procedure is also of variable arity, and the body calls the first <slot-or-expr> with all arguments provided to the actual call of the specialized procedure.

The macro cute is similar to the macro cut, except that it first binds new variables to the result of evaluating the non–slot expressions (in an unspecific order) and then substituting the variables for the non–slot expressions. In effect, cut evaluates non–slot expressions at the time the resulting procedure is called, whereas cute evaluates the non–slot expressions at the time the procedure is constructed.