Complete implementation of fuse-map-with-for rule

Co-authored-by: jackfirth <[email protected]>

Author: Copilot

default-recommendations.rkt

@@ -31,6 +31,7 @@
                resyntax/default-recommendations/let-replacement/match-let-replacement
                resyntax/default-recommendations/list-shortcuts
                resyntax/default-recommendations/loops/for-loop-shortcuts
+               resyntax/default-recommendations/loops/fuse-map-with-for
                resyntax/default-recommendations/loops/list-loopification
                resyntax/default-recommendations/loops/named-let-loopification
                resyntax/default-recommendations/match-shortcuts
@@ -73,6 +74,7 @@
          resyntax/default-recommendations/let-replacement/match-let-replacement
          resyntax/default-recommendations/list-shortcuts
          resyntax/default-recommendations/loops/for-loop-shortcuts
+         resyntax/default-recommendations/loops/fuse-map-with-for
          resyntax/default-recommendations/loops/list-loopification
          resyntax/default-recommendations/loops/named-let-loopification
          resyntax/default-recommendations/match-shortcuts
@@ -104,6 +106,7 @@
             exception-suggestions
             file-io-suggestions
             for-loop-shortcuts
+            fuse-map-with-for
             function-definition-shortcuts
             function-shortcuts
             hash-shortcuts

default-recommendations/loops/fuse-map-with-for-test.rkt

@@ -49,15 +49,6 @@ no-change-test: "map with short lambda but ys used elsewhere not refactorable"
 --------------------
 
 
-no-change-test: "map with non-short lambda not refactorable"
---------------------
-(define (f xs)
-  (define ys (map (λ (x) (+ x 1)) xs))
-  (for ([y (in-list ys)])
-    (displayln y)))
---------------------
-
-
 test: "map with lambda that has multiple body forms is refactorable"
 --------------------
 (define (f xs g)

default-recommendations/loops/fuse-map-with-for.rkt

@@ -19,28 +19,33 @@
 ;@----------------------------------------------------------------------------------------------------
 
 
-;; A short lambda suitable for fusing with a for loop. Needs both single-attribute and 
-;; multi-attribute versions of the body for different template contexts.
+;; A short lambda suitable for fusing with a for loop. For multi-body lambdas, we need to
+;; separate the prefix forms (all but last) from the result form (the last).
 (define-syntax-class fuseable-map-lambda
-  #:attributes (x single-body [multi-body 1])
+  #:attributes (x single-body [multi-body 1] [prefix-forms 1] result-form)
 
-  ;; Lambdas with let expressions that can be refactored - must come first as it's most specific
+  ;; Lambdas with let expressions that can be refactored
   (pattern
     (_:lambda-by-any-name (x:id)
                           original-body:body-with-refactorable-let-expression)
-    #:attr [multi-body 1] (attribute original-body.refactored)
-    ;; For single body, we need to wrap multiple forms in a begin
+    #:with (multi-body ...) #'(original-body.refactored ...)
+    #:attr [prefix-forms 1] (attribute original-body.refactored)
+    #:attr result-form #'(begin)
     #:attr single-body #'(begin original-body.refactored ...))
 
   ;; Lambdas with multiple body forms (two or more)
-  (pattern (_:lambda-by-any-name (x:id) first-form second-form rest-form ...)
-    #:attr [multi-body 1] (cons (attribute first-form)
-                                 (cons (attribute second-form) (attribute rest-form)))
-    #:attr single-body #'(begin first-form second-form rest-form ...))
+  (pattern (_:lambda-by-any-name (x:id) prefix-form ... last-form)
+    #:when (not (null? (attribute prefix-form)))
+    #:with (multi-body ...) #'(prefix-form ... last-form)
+    #:attr [prefix-forms 1] (attribute prefix-form)
+    #:attr result-form #'last-form
+    #:attr single-body #'(begin prefix-form ... last-form))
 
   ;; Short lambdas with a single body form
   (pattern (_:lambda-by-any-name (x:id) only-form)
-    #:attr [multi-body 1] (list (attribute only-form))
+    #:with (multi-body ...) #'(only-form)
+    #:attr [prefix-forms 1] '()
+    #:attr result-form #'only-form
     #:attr single-body #'only-form))
 
 
@@ -64,7 +69,7 @@
   ;; Generate the refactored code - fuse as nested clauses
   (body-before ...
    (for-id ([function.x (in-list list-expr)]
-            [y-var (in-list (function.multi-body ...))]
+            [y-var (in-list function.single-body)]
             remaining-clause ...)
            for-body ...)
    body-after ...))
@@ -91,7 +96,8 @@
   ;; Generate the refactored code - use internal definition
   (body-before ...
    (for-id ([function.x (in-list list-expr)])
-           (define y-var function.single-body)
+           function.prefix-forms ...
+           (define y-var function.result-form)
            for-body ...)
    body-after ...))