719 ;;Quote: applicative languages evaluate expressions within an environment; the environment binds variables to values

719 ;;Quote: a function is a value that can be "applied" to its arguments

719 ;;Quote: function application and expression evaluation may never produce a result; never terminates or stops with an error

719 ;;Quote: in a purely applicative language, function application to known arguments always produces the same result; same for expression evaluation

720 ;;Quote: call-by-value if evaluate arguments before function, call-by-name if evaluate on each reference; use left-to-right evaluation to support extensions under call-by-value

722 ;;Quote: use abstract syntax instead of strings to represent programs in the defining language; avoids parsing into structured data objects; e.g., integers vs. digit strings

722 ;;Quote: use abstract syntax expressions to define, construct, analyze, and classify sets of abstract expressions; e.g., APPL = [opr: EXP, opnd: EXP] defines a set APPL, selectors opr and opnd, classifier appl?, and constructor mk-appl

722+;;Quote: APPL = [opr: EXP, opnd: EXP] defines a set APPL, selectors opr and opnd, classifier appl?, and constructor mk-appl

723 ;;Quote: define the set CONST by functions const? and evcon; evcon maps each constant into the value it denotes

724 ;;Quote: a meta-circular interpreter for expression evaluation defines each feature of the defined language via the corresponding feature of the defining language

725 ;;Quote: a meta-circular interpreter does not explain higher-order functions, does not support both call-by-value and call-by-name, and does not support extensions

726 ;;Quote: replace function arguments and results by records which represent functions, an 'apply' function to interpret these records, and an environment that binds values to variables; like LISP

730 ;;Quote: use continuations to isolate serious operands, expressions, and functions that might not terminate; allows call-by-value or call-by-name

733 ;;Quote: a continuation is a linear list of instructions; an interpreter of continuations is a state-transition machine, somewhat like Landin's SECD machines

735 ;;Quote: an escape expression is like jumping to a label while passing an argument; applies a higher-order continuation