AoC 2020.1 p1

2 files changed, 35 insertions, 0 deletions

diff --git a/iterative-add/iterative-add-test.scm b/iterative-add/iterative-add-test.scm
new file mode 100644
index 0000000..d318570
--- /dev/null
+++ b/iterative-add/iterative-add-test.scm
@@ -0,0 +1,20 @@
+;; -*- compile-command: "guile -L . iterative-add-test.scm"; -*-
+(use-modules (srfi srfi-64)
+	     (iterative-add))
+
+
+(test-begin "harness")
+
+(test-equal "add 0 to 1"
+  1
+  (iterative-add-generator 1))
+
+(test-equal "add 1 to 2"
+  3
+  (iterative-add-generator 2))
+
+(test-equal "add 2 to 6"
+  8
+  (iterative-add-generator 6))
+
+(test-end "harness")
diff --git a/iterative-add/iterative-add.scm b/iterative-add/iterative-add.scm
new file mode 100644
index 0000000..45c6cf9
--- /dev/null
+++ b/iterative-add/iterative-add.scm
@@ -0,0 +1,15 @@
+(define-module (iterative-add)
+  #:export (iterative-add-generator))
+
+(define iterative-add
+  (let ((prev-num 0))
+    (lambda (num)
+      (let ((result
+	     (+ num prev-num)))
+	(set! prev-num num)
+	result))))
+
+(define (iterative-add-generator num)
+  "Adds the previously received
+number to the current one."
+  (iterative-add num))