tree map

README.md

@@ -44,4 +44,4 @@ Also take note of the fact that I typically compile everything with `-S` and `-O
 
 ## The Core Library
 
-One of the unfortunate consequences of the way OCaml's compilation works, is that there is a library called the core library, documented [here](https://ocaml.org/manual/core.html), which contains some definitions for types and exceptions, yet does not include the code from the stdlib that uses them. When compiling with the `-nopervasives` flag, this is still included but without the standard library. While this makes sense from the perspective of having some fundamental exceptions always available, having types like `list` included makes it very annoying when implemented a custom standard library. This quirk is why my library has no type definition for `list`, `bool`, `option`, etc. but still uses these types.
+One of the unfortunate consequences of the way OCaml's compilation works, is that there is a library called the core library, documented [here](https://ocaml.org/manual/core.html), which contains some definitions for types and exceptions, yet does not include the code from the stdlib that uses them. When compiling with the `-nopervasives` flag, this is still included but without the standard library. While this makes sense from the perspective of having some fundamental exceptions always available, having types like `list` included makes it very annoying when implemented a custom standard library. This quirk is why my library has no type definition for `list`, `bool`, `option`, etc. but still uses these types.

lib/tree.ml

@@ -1,5 +1,10 @@
-open List
+open FromStdlib
 open Types
 
 let combine (tr1 : 'a tree) (tr2 : 'a tree) (topBranch : 'a) : 'a tree =
-    Branch (topBranch, tr1 :: tr2 :: [])
+    Branch (topBranch, tr1 :: tr2 :: [])
+
+let rec map (f : 'a -> 'b) (tr : 'a tree) : 'b tree =
+    match tr with
+    | Branch (value, branches) -> Branch (f value, branches |> List.map (map f))
+    | Leaf -> Leaf

lib/tree.mli

@@ -1,4 +1,7 @@
 open Types
 
 (* Combines two trees of the same type, with the specified value at the new top node. Runs in O(1). *)
-val combine : 'a tree -> 'a tree -> 'a -> 'a tree
+val combine : 'a tree -> 'a tree -> 'a -> 'a tree
+
+(** Applies the provided function to each element of the tree. Does not use constant stack space. Runs in O(n). *)
+val map : ('a -> 'b) -> 'a tree -> 'b tree