[peetle]

You should definitely check out the work going on in Dynamo right now: https://github.com/DynamoDS/Dynamo We've put a huge amount of work into this problem.

Dynamo has the notion of a "custom node." This is essentially a lambda. It is represented by a "nested" set of nodes, making up the function body.

There's a bunch more stuff going on there - including compiling nodes to a domain specific, associative language called DesignScript.