reduce some memory use of `unstable' doc build

by explicitly closing evaluators

collects/unstable/scribblings/class-iop.scrbl

@@ -126,3 +126,5 @@ unsound in the presence of mutation from outside the class. This
 should be fixed.
 
 }
+
+@close-eval[the-eval]

collects/unstable/scribblings/find.scrbl

@@ -75,3 +75,5 @@ procedure or returned otherwise.
 (find-first symbol? (shared ([x (cons 'a x)]) x))
 ]
 }
+
+@close-eval[the-eval]

collects/unstable/scribblings/generics.scrbl

@@ -135,4 +135,6 @@ Syntactically an error when used outside @racket[define-methods].
 (gen-print y)
 (gen-port-print (current-output-port) y)
 (gen-print* y #:width 100 #:height 90)
-]
+]
+
+@close-eval[evaluator]

collects/unstable/scribblings/list.scrbl

@@ -118,3 +118,4 @@ for which @racket[pred] produces a true value.
 
 }
 
+@close-eval[the-eval]

collects/unstable/scribblings/match.scrbl

@@ -69,3 +69,5 @@ result value of @scheme[rhs-expr], and continues matching each subsequent
 ]
 
 }
+
+@close-eval[the-eval]

collects/unstable/scribblings/mutated-vars.scrbl

@@ -36,3 +36,5 @@ Otherwise, the table is updated functionally.}
 (dict-ref tbl #'var #f)
 ]
 }
+
+@close-eval[the-eval]

collects/unstable/scribblings/prop-contract.scrbl

@@ -50,3 +50,5 @@ The contract has no effect on the struct type property accessor.
 ((get-f s2) 'apple)
 ]
 }
+
+@close-eval[the-eval]

collects/unstable/scribblings/sequence.scrbl

@@ -40,4 +40,6 @@ Produces the sequence of @racket[f] applied to each element of @racket[seq].
 @examples[#:eval the-eval
 (for/list ([x (sequence-lift add1 (in-range 10))])
   x)]
-}
+}
+
+@close-eval[the-eval]

collects/unstable/scribblings/sexp-diff.scrbl

@@ -25,3 +25,6 @@
 
  @examples[#:eval diff-eval (sexp-diff '(0 (1 2 3)) '(0 (4 2 3)))]
 }
+
+
+@close-eval[diff-eval]

collects/unstable/scribblings/srcloc.scrbl

@@ -330,3 +330,5 @@ b-path
 ]
 
 }
+
+@close-eval[evaluator]

collects/unstable/scribblings/struct.scrbl

@@ -56,3 +56,5 @@ the inaccessible fields are omitted from the list.
 (struct->list 'not-a-struct #:on-opaque 'skip)
 ]
 }
+
+@close-eval[the-eval]

collects/unstable/scribblings/syntax.scrbl

@@ -484,3 +484,5 @@ non-syntax data, and @scheme[quote-syntax] does the opposite.
 ]
 
 }
+
+@close-eval[the-eval]

collects/unstable/scribblings/wrapc.scrbl

@@ -122,3 +122,5 @@ contract wrapping.
 (app (lambda (x) 'pear) 5)
 ]
 }
+
+@close-eval[the-eval]