Add begin splicing rules

Closes #375.

default-recommendations/definition-shortcuts-test.rkt

@@ -192,3 +192,31 @@ test: "inlining immediately returned variable definition respects requested line
   (define x 1)
   x)
 ------------------------------
+
+
+test: "begin in right hand side of definition can be removed"
+--------------------
+(define (foo)
+  (define x (begin (displayln "foo") 42))
+  (* x 2))
+--------------------
+--------------------
+(define (foo)
+  (displayln "foo")
+  (define x 42)
+  (* x 2))
+--------------------
+
+
+test: "begin0 in right hand side of definition can be removed"
+--------------------
+(define (foo)
+  (define x (begin0 42 (displayln "foo")))
+  (* x 2))
+--------------------
+--------------------
+(define (foo)
+  (define x 42)
+  (displayln "foo")
+  (* x 2))
+--------------------

default-recommendations/definition-shortcuts.rkt

@@ -42,6 +42,34 @@
   (body-before ... focused))
 
 
+(define-definition-context-refactoring-rule define-begin-extraction
+  #:description
+  "The `begin` in this definition can be extracted into the surrounding definition context."
+  #:literals (define begin)
+  (~seq body-before ...
+        (~and definition (define id (begin pre-body ... expr)))
+        body-after ...)
+  #:with (replacement ...)
+  #'(~focus-replacement-on
+     (~splicing-replacement (pre-body ... (define id expr)) #:original definition))
+  (body-before ... replacement ... body-after ...))
+
+
+(define-definition-context-refactoring-rule define-begin0-extraction
+  #:description
+  "The `begin0` in this definition can be extracted into the surrounding definition context."
+  #:literals (define begin0)
+  (~seq body-before ...
+        (~and definition (define id (begin0 expr post-body ...)))
+        body-after ...)
+  #:with (replacement ...)
+  #'(~focus-replacement-on
+     (~splicing-replacement ((define id expr) post-body ...) #:original definition))
+  (body-before ... replacement ... body-after ...))
+
+
 (define-refactoring-suite definition-shortcuts
-  #:rules (define-values-values-to-define
+  #:rules (define-begin-extraction
+            define-begin0-extraction
+            define-values-values-to-define
             inline-unnecessary-define))