add new recipe

Author: jcubic

generate.js

@@ -21,8 +21,8 @@ function get_api(argv) {
     const re = /\[Recipe\]/;
     return get(`https://api.github.com${base_path}`, { query, auth }).then(function(issues) {
         issues.forEach(function(issue) {
-            const { title, url } = issue;
-            if (title.match(re)) {
+            const { title, url, state } = issue;
+            if (title.match(re) && state == 'open') {
                 const filename = './recipes/' + slugify(title.replace(re, '')) + '.md';
                 get(url, { auth }).then(function(issue) {
                     const { body } = issue;

recipes/searching-sub-string-inside-a-string.md

@@ -0,0 +1,43 @@
+## Problem
+
+You want to search and find the index of a string inside a bigger string.
+
+## Solution
+
+```scheme
+(define (string-find haystack needle . rest)
+  (let ((start (if (null? rest) 0 (car rest))))
+    (let* ((haystack-len (string-length haystack))
+           (needle-len (string-length needle))
+           (start 0))
+      (let loop ((h-index start)
+                 (n-index 0))
+        (let ((h-char (string-ref haystack h-index))
+              (n-char (string-ref needle n-index)))
+          (if (char=? h-char n-char)
+              (if (= (+ n-index 1) needle-len)
+                  (+ (- h-index needle-len) 1)
+                  (loop (+ h-index 1) (+ n-index 1)))
+              (if (= (+ h-index 1) haystack-len)
+                  #f
+                  (loop (+ h-index 1) 0))))))))
+```
+
+### SRFI
+
+The same functionality is provided by SRFI-13 function `string-contains` and `string-contains-ci`
+
+Credit: [Jakub T. Jankiewicz](https://jcubic.pl/me)
+
+## Usage
+
+```scheme
+(let* ((input "This is hello world")
+       (search "hello")
+       (found (string-find input search)))
+  (if found
+      (begin
+        (display (substring input found))
+        (newline))))
+;; ==> "helo world"
+```