The duplication there in each AST node kinda hurts the eyes :) Also, the type-switch on interface {} is ugly. Consider how an AST looks like in Haskell: da

The duplication there in each AST node kinda hurts the eyes :) Also, the type-switch on interface {} is ugly. Consider how an AST looks like in Haskell: data AST = LiteralInt Int | LiteralFloat Float | List [AST] ... And then an eval looks like: case ast of LiteralInt int -> ... LiteralFloat float -> ... List nodes -> ... and it is safe, rather than interface{}, you get the AST type and you get exhaustiveness checking that you covered all cases. Also, if you add an annotation to each AST element (e.g: inferred types), you can very easily and safely map over them, etc.