Add refactoring rule for sequence-tail with in-vector (#738)

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: jackfirth <[email protected]>

Author: Copilot

default-recommendations/loops/for-loop-shortcuts-test.rkt

@@ -563,3 +563,56 @@ test: "shadowed and unused in-value clause refactorable to #:do clause"
        [b (in-range 0 a)])
   (displayln (list a b)))
 --------------------
+
+
+test: "sequence-tail with in-vector refactorable to in-vector with start index"
+--------------------
+(require racket/sequence)
+(define vec (vector 1 2 3 4 5))
+(for ([x (sequence-tail (in-vector vec) 2)])
+  (displayln x))
+====================
+(require racket/sequence)
+(define vec (vector 1 2 3 4 5))
+(for ([x (in-vector vec 2)])
+  (displayln x))
+--------------------
+
+
+test: "sequence-tail with in-vector and variable start index refactorable"
+--------------------
+(require racket/sequence)
+(define vec (vector 1 2 3 4 5))
+(define start-idx 3)
+(for ([x (sequence-tail (in-vector vec) start-idx)])
+  (displayln x))
+====================
+(require racket/sequence)
+(define vec (vector 1 2 3 4 5))
+(define start-idx 3)
+(for ([x (in-vector vec start-idx)])
+  (displayln x))
+--------------------
+
+
+test: "sequence-tail with in-vector in for/list refactorable"
+--------------------
+(require racket/sequence)
+(define vec (vector 1 2 3 4 5))
+(for/list ([x (sequence-tail (in-vector vec) 1)])
+  (* x 2))
+====================
+(require racket/sequence)
+(define vec (vector 1 2 3 4 5))
+(for/list ([x (in-vector vec 1)])
+  (* x 2))
+--------------------
+
+
+no-change-test: "sequence-tail with non-in-vector sequence not refactorable"
+--------------------
+(require racket/sequence)
+(define lst (list 1 2 3 4 5))
+(for ([x (sequence-tail (in-list lst) 2)])
+  (displayln x))
+--------------------

default-recommendations/loops/for-loop-shortcuts.rkt

@@ -11,6 +11,7 @@
 
 (require (for-syntax racket/base)
          racket/list
+         racket/sequence
          racket/set
          resyntax/base
          resyntax/default-recommendations/analyzers/identifier-usage
@@ -299,6 +300,13 @@ return just that result."
   (for-id (clause-before ... #:do [expr] clause-after ...) body ...))
 
 
+(define-refactoring-rule sequence-tail-in-vector-to-in-vector
+  #:description "The `in-vector` function accepts an optional start index, making `sequence-tail` unnecessary."
+  #:literals (sequence-tail in-vector)
+  (sequence-tail (in-vector vec) start)
+  (in-vector vec start))
+
+
 (define-refactoring-suite for-loop-shortcuts
   #:rules (for/fold-building-hash-to-for/hash
            for/fold-result-keyword
@@ -314,5 +322,6 @@ return just that result."
            nested-for/and-to-for*/and
            nested-for/or-to-for*/or
            or-let-in-for/and-to-filter-clause
+           sequence-tail-in-vector-to-in-vector
            unless-expression-in-for-loop-to-unless-keyword
            when-expression-in-for-loop-to-when-keyword))