Add build-list-to-for rule (#473)

Closes #384.

Author: jackfirth

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

@@ -262,6 +262,44 @@ test: "hash-for-each with let expression refactorable to for with definitions"
 ------------------------------
 
 
+test: "build-list with short single-body form not refactorable"
+- (build-list 10 (λ (i) (* i 2)))
+
+
+test: "build-list with long single-body form refactorable to for/list"
+------------------------------
+(build-list 10
+            (λ (a-very-very-very-long-variable-name-thats-so-very-long)
+              (* a-very-very-very-long-variable-name-thats-so-very-long 2)))
+------------------------------
+------------------------------
+(for/list ([a-very-very-very-long-variable-name-thats-so-very-long (in-range 10)])
+  (* a-very-very-very-long-variable-name-thats-so-very-long 2))
+------------------------------
+
+
+test: "build-list with multiple body forms refactorable to for/list"
+------------------------------
+(build-list 10 (λ (i) (displayln i) (* i 2)))
+------------------------------
+------------------------------
+(for/list ([i (in-range 10)])
+  (displayln i)
+  (* i 2))
+------------------------------
+
+
+test: "build-list with let expression refactorable to for/list"
+------------------------------
+(build-list 10 (λ (i) (let ([j (* i 2)]) (list i j))))
+------------------------------
+------------------------------
+(for/list ([i (in-range 10)])
+  (define j (* i 2))
+  (list i j))
+------------------------------
+
+
 test: "ormap to for/or"
 ------------------------------
 (define some-list (list 3 5 14 10 6 5 2))

default-recommendations/for-loop-shortcuts.rkt

@@ -176,6 +176,14 @@
     function.body ...))
 
 
+(define-refactoring-rule build-list-to-for
+  #:description "This `build-list` operation can be replaced with a `for/list` loop."
+  #:literals (build-list)
+  (build-list n function:worthwhile-loop-body-function)
+  (for/list ([function.x (in-range n)])
+    function.body ...))
+
+
 (define-syntax-class for-loop-supporting-leading-nested-clause
   #:literals (for/list for*/list)
   #:attributes ([clause 1] [body 1])
@@ -530,6 +538,7 @@ return just that result."
   #:rules (andmap-to-for/and
            append-map-for/list-to-for*/list
            apply-plus-to-for/sum
+           build-list-to-for
            for/fold-building-hash-to-for/hash
            for/fold-result-keyword
            for/fold-with-conditional-body-to-unless-keyword