simplified seed-maps-processor

day05-hard/main.scm

@@ -25,13 +25,6 @@
 (define (is-not value) (lambda (x) (not (equal? x value))))
 (define (is-not-empty value) (not (null? value)))
 
-;=============== prepend ======================
-(define (prepend first-value) (lambda (rest) (cons first-value rest)))
-
-(assert-eq "prepend test failed"
-  '(1 2 3 4)
-  ((prepend 1) '(2 3 4)))
-
 ;=============== combinators ======================
 (define (Y f) (f (lambda (x) ((Y f) x))))
 (define (Y2 f) (f (lambda (x y) ((Y2 f) x y))))
@@ -72,6 +65,20 @@
     (lambda (current accumulator) (cons (+ 1 (car accumulator)) (cons current accumulator))))
     '(101 102 103 104)))
 
+;=============== prepend ======================
+(define (prepend first-value) (lambda (rest) (cons first-value rest)))
+
+(assert-eq "prepend test failed"
+  '(1 2 3 4)
+  ((prepend 1) '(2 3 4)))
+
+;=============== append ======================
+(define (append first-value) (reduce-right (list first-value) cons))
+
+(assert-eq "append test failed"
+  '(1 2 3 4)
+  ((append 4) '(1 2 3)))
+
 ;=============== reverse ======================
 (define reverse (reduce-left '() cons))
 
@@ -433,13 +440,12 @@
     (get-range-start state-value)
     (get-range-end state-value)))
 
-(define (seed-maps-processor seed-maps)
+(define seed-maps-processor
   (compose (list
-    ;; for state
-    #!(tee-with-comment "state after applying mapset")!#
-    ((compose (list
     ;; for list of maps (within a single map set); returns state-transforming lambda
     compose
+    #!(prepend (tee-with-comment "state after applying mapset"))!#
+    (append swap-state)
     (map (lambda (seed-map)
       ;; for seed map within the list: returns state-transforming lambda
       (compose (list
@@ -449,9 +455,7 @@
           (if
             (is-state-value-current state-entry)
             (list state-entry)
-              (apply-map-to-previous-state-value seed-map (get-state-value state-entry)))))))))))
+            (apply-map-to-previous-state-value seed-map (get-state-value state-entry))))))))))))
-      seed-maps)
-    swap-state)))
 
 (define parse-seed-maps
   (compose (list