move examples to examples/ directory, add for loop example

Makefile

@@ -64,7 +64,7 @@ wasm/wasm_exec.html:
 
 test: grol
 	CGO_ENABLED=0 go test -tags $(GO_BUILD_TAGS) ./...
-	./grol *.gr
+	./grol examples/*.gr
 
 generate:
 	go generate ./... # if this fails go install golang.org/x/tools/cmd/stringer@latest

README.md

@@ -54,11 +54,13 @@ print, log
 
 macros and more all the time
 
-See also [sample.gr](sample.gr) that you can run with
+See also [sample.gr](examples/sample.gr) and others in that folder, that you can run with
 ```
-gorepl *.gr
+gorepl examples/*.gr
 ```
 
+or copypaste to the online version on [grol.io](https://grol.io)
+
 ## Dev mode:
 ```shell
 go install golang.org/x/tools/cmd/stringer@latest

examples/for.gr

@@ -0,0 +1,18 @@
+// for loop example, functional style
+// executes with 1..n passed to the function parameter.
+
+for=func(n, f) {
+    l=func(i,f) { // internal lambda with the index param
+       r = f(i)
+       if (i>=n) {
+           return r
+       }
+       l(i+1, f)
+    }
+    l(1,f)
+}
+
+for(5, func(n) {
+   log("n is", n)
+   n // return value at the end
+})