diff --git a/collects/unstable/sequence.rkt b/collects/unstable/sequence.rkt
index 7f9ce96b41..be7721a421 100644
--- a/collects/unstable/sequence.rkt
+++ b/collects/unstable/sequence.rkt
@@ -6,6 +6,10 @@
 
 (provide in-syntax in-pairs in-sequence-forever sequence-lift)
 
+;; ELI: I don't see a point in this over using `syntax->list' directly.
+;; (Eg, the latter is something that can be used when the programmer
+;; knows that it's a list, in contrast to this code which will just
+;; throw an error.)
 (define-sequence-syntax in-syntax
   (λ () #'(λ (e) (in-list (syntax->list e))))
   (λ (stx)
@@ -13,6 +17,8 @@
       [[ids (_ arg)]
        #'[ids (in-list (syntax->list arg))]])))
 
+;; ELI: This is very specific, and indeed there are no uses of it
+;; anywhere in the tree other than in TR where it came from.
 (define (in-pairs seq)
   (make-do-sequence
    (λ ()
@@ -24,6 +30,8 @@
                (λ _ #t)
                (λ _ #t))))))
 
+;; ELI: Besides the awful name, this is the same as
+;;      (in-sequences seq (in-cycle (in-value val)))
 (define (in-sequence-forever seq val)
   (make-do-sequence
    (λ ()
@@ -35,6 +43,7 @@
                (λ _ #t)
                (λ _ #t))))))
 
+;; ELI: How is this different from `sequence-map'?
 (define (sequence-lift f seq)
   (make-do-sequence
    (λ ()
@@ -52,16 +61,19 @@
  [in-slice (exact-positive-integer? any/c . -> . any)])
 
 (define (in-slice k seq)
+  ;; ELI: what's the point of using `any/c' above and then checking it here?
   (unless (sequence? seq) (raise-type-error 'in-slice "sequence" seq))
   (make-do-sequence
    (λ ()
      (define-values (more? get) (sequence-generate seq))
      (values
       (λ (_)
+        ;; ELI: Add an `in-range'
         (for/list ([i k] #:when (more?))
           (get)))
       values
       #f
       #f
+      ;; ELI: Use `pair?'
       (λ (val) (0 . < . (length val)))
       #f))))