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@@ -14382,6 +14382,81 @@ symbols in .code lambda whereas the interpreter ignores the situation. +Note: it is not always necessary to use the +.code lambda +operator directly in order to produce an anonymous function. + +In situations when +.code lambda +is being written in order to simulate partial evaluation, it may be possible +to instead make use of the +.code op +macro. For instance the function +.code "(lambda (. args) [apply + a args])" +which adds the values of all of its arguments together, and to the lexically +captured variable +.code a +can be written more succinctly as +.codn "(op + a)" . +The +.code op +operator is the main representative of a family of operators: +.codn lop , +.codn ap , +.codn ip , +.codn do , +.codn ado , +.code opip +and +.codn oand . + +In situations when functions are simply combined together, the effect +may be achieved using some of the available functional combinators, +instead of a +.codn lambda . +For instance chaining together functions as in +.code "(lambda (x) (square (cos x)))" +is achievable using the +.code chain +function: +.codn "[chain cos square]" . +The +.code opip +operator can also be used: +.codn "(opip cos square)" . +Numerous combinators are available; see the section Partial Evaluation and +Combinators. + +When a function is needed which accesses an object, there are also +alternatives. Instead of +.code "(lambda (obj) obj.slot)" +and +.code "(lambda (obj arg) obj.(slot arg))" +it is possible to simply the +.code ".slot" +and +.code ".(slot arg)" +notations. See the section Unbound Referencing Dot. +Also see the functions +.code umethod +and +.code uslot +as well as the related convenience macros +.code umeth +and +.codn usl . + +If a function is needed which partially applies some arguments +to the method invoked on a specific object, the +.code method +function or +.code meth +macro may be used. For instance, instead of +.codn "(lambda (arg) obj.(method 3 arg))" , +it is possible to write +.code "(meth obj 3)" +except that the latter produces a variadic function. + .TP* Examples: .IP "Counting function:" This function, which takes no arguments, captures the |