metago

Playing around with metaprogramming in go.

• https://www.youtube.com/watch?v=aI_XdjQwTCU
• http://www.lshift.net/blog/2011/04/30/using-the-syntax-tree-in-go/
• http://stackoverflow.com/questions/23923383/evaluate-formula-in-go
• See second comment, go has an rpc server thing??? That looks cool: http://stackoverflow.com/questions/37122401/execute-another-go-program-from-within-a-golang-program
• https://github.com/xtaci/goeval

Recursive Visualization

The initial inspiration for creating this repository was that I wanted to write a program to "visualize" the recursive calls that get made for an arbitrary function. I just thought it would be a fun thing to do! For example, if we have this fibonacci function:

func fib(n int) int {
	if n < 2 {
		return n
	}
	return fib(n-1) + fib(n-2)
}

Then doing something like: visualizeRecFnCalls("fib", "4") will print out:

fib(4)
-fib(3)
--fib(2)
---fib(1)
---fib(0)
--fib(1)
-fib(2)
--fib(1)
--fib(0)

I suppose you could generalize this and visualize all function calls that get made or perhaps a subset of functions. Maybe I'll do that someday but this is fine for now. I wouldn't be surprised if someone has done that actually, I should try to find it.

TODO:

I finished the super MVP of the above description but there are a lot of other things I could do related to it:

1. Look into how go test constructs a main package and executes it. After looking at it for a while I'm getting the feeling that they also do the equivalent of just calling go run like I'm doing but I'm not sure.
2. Generate a random file name that we will call go run on so we don't run into any file conflict issues.
3. Dynamically generate the imports of the generated file. Right now they are just statically there so if the function I am visualizing uses packages other than "fmt" and "strings" then it won't work.
4. Dynamically construct the "depth" identifier name just in case the recursive function uses that name in its definition.
5. If something goes wrong with the go run I don't think I'm getting stderr which makes it a bit harder to debug if something goes wrong. How do I get stderr when executing a program?
6. Put the "visualize" function into a library rather than just having it in the main package.
7. When searching through the go test code I saw something about examples: /usr/local/Cellar/go/1.6/libexec/src/cmd/go/test.go 1361. And after noticing that I did notice more that the standard library documentation has these "Examples" sections. Learn more about these.