attempt from scratch

sh/doc.awk

@@ -0,0 +1,73 @@
+function append(line) {
+    if (doc) {
+        doc = doc "\n"
+    }
+    doc = doc line
+}
+
+function output(name) {
+    print name
+    print "↓"
+    print doc
+    exit
+}
+
+function reset() {
+    doc = ""
+}
+
+BEGIN {
+    RE_ANY = "(.*)"
+    RE_NAME = "([_A-Za-z][_0-9A-Za-z]*)"
+    RE_SPACE = "[[:space:]]"
+    RE_SPACES = RE_SPACE "*"
+
+    RE_BEGIN = "^"
+    RE_END = RE_SPACES "$"
+    RE_FUNC = RE_SPACES "\\(" RE_SPACES "\\)" RE_SPACES "{"
+
+    RE_ALIAS = RE_BEGIN "#\\(" RE_SPACES RE_NAME RE_END
+    RE_DOC = RE_BEGIN "#" RE_SPACE RE_ANY RE_END
+    RE_FUNCTION = RE_BEGIN RE_NAME RE_FUNC RE_END
+    RE_MODULE = RE_BEGIN "#." RE_SPACES RE_NAME RE_END
+    RE_SET = RE_BEGIN RE_NAME "=.*" RE_END
+    RE_SHEBANG = RE_BEGIN "#!" RE_SPACES RE_ANY RE_END
+
+    alias = 0
+    reset()
+    module = 0
+}
+
+{
+    if (match($0, RE_MODULE, m)) {
+        reset()
+        if (m[1] == target) {
+            module = 1
+        }
+    } else if (match($0, RE_SHEBANG, m)) {
+        append(m[1])
+    } else if (match($0, RE_DOC, m)) {
+        append(m[1])
+    } else if (match($0, RE_SET, m)) {
+        if (m[1] == target) {
+            output(m[1])
+        } else {
+            reset()
+        }
+    } else if (match($0, RE_ALIAS, m)) {
+        if (m[1] == target) {
+            alias = 1
+        }
+        append(m[1])
+    } else if (match($0, RE_FUNCTION, m)) {
+        if (alias) {
+            output(m[1])
+        } else if (m[1] == target) {
+            output(m[1])
+        } else {
+            reset()
+        }
+    } else {
+        reset()
+    }
+}

sh/main.sh

@@ -64,6 +64,7 @@ rwx_main() {
 # ╰──────┴───────╯
 
 # cache source code of a module
+# inside a global code variable
 rwx_cache() {
 	local root="${1}"
 	local module="${2}"

sh/self.sh

@@ -1,4 +1,5 @@
-# self module
+# self
+# module
 
 # meta doc
 rwx_doc() {