The Metacircular Evaluator $($Racket Language$)$

Add the following primitives: and error to mceval. rkt $.$

Your error primitive should take no arguments and abort the interpreter with the message "Metacircular Interpreter Aborted" $($without the quotes$).$ You

should use Racket's error function to raise an exception like this:

$($error "Metacircular Interpreter Aborted"$)$

$($define $($mceval exp env$)$

$($cond $(($self$-$evaluating? exp$)$ exp$)$

$(($variable$?$ exp$)($lookup$-$variable$-$value exp env$))$

$(($quoted$?$ exp$)($text$-$of$-$quotation exp$))$

$(($assignment$?$ exp$)($eval$-$assignment exp env$))$

$(($definition$?$ exp$)($eval$-$definition exp env$))$

$(($if$?$ exp$)($eval$-$if exp env$))$

$(($lambda$?$ exp$)$

$($make$-$procedure $($lambda$-$parameters exp$)$

$($lambda$-$body exp$)$

env$))$

$(($begin$?$ exp$)$

$($eval$-$sequence $($begin$-$actions exp$)$ env$))$

$(($cond$?$ exp$)($mceval $($cond$->$if exp$)$ env$))$

$(($application$?$ exp$)$

$($mcapply $($mceval $($operator exp$)$ env$)$

$($list$-$of$-$values $($operands exp$)$ env$)))$

$($else

$($error "Unknown expression type $--$ EVAL" exp$))))$

$($define $($mcapply procedure arguments$)$

$($cond $(($primitive$-$procedure? procedure$)$

$($apply$-$primitive$-$procedure procedure arguments$))$

$(($compound$-$procedure? procedure$)$

$($eval$-$sequence

$($procedure$-$body procedure$)$

$($extend$-$environment

$($procedure$-$parameters procedure$)$

arguments

$($procedure$-$environment procedure$))))$

$($else

$($error

"Unknown procedure type $--$ APPLY" procedure$))))$

$($define $($list$-$of$-$values exps env$)$

$($if $($no$-$operands? exps$)$

$\text{'}()$

$($cons $($mceval $($first$-$operand exps$)$ env$)$

$($list$-$of$-$values $($rest$-$operands exps$)$ env$))))$

$($define $($eval$-$if exp env$)$

$($if $($true$?($mceval $($if$-$predicate exp$)$ env$))$

$($mceval $($if$-$consequent exp$)$ env$)$

$($mceval $($if$-$alternative exp$)$ env$)))$

$($define $($eval$-$sequence exps env$)$

$($cond $(($last$-$exp? exps$)($mceval $($first$-$exp exps$)$ env$))$

$($else $($mceval $($first$-$exp exps$)$ env$)$

$($eval$-$sequence $($rest$-$exps exps$)$ env$))))$

$($define $($eval$-$assignment exp env$)$

$($set$-$variable$-$value! $($assignment$-$variable exp$)$

$($mceval $($assignment$-$value exp$)$ env$)$

env$)$

$\text{'}$ok$)$

$($define $($eval$-$definition exp env$)$

$($define$-$variable! $($definition$-$variable exp$)$

$($mceval $($definition$-$value exp$)$ env$)$

env$)$

$\text{'}$ok$)$