Initial state - basic lexer + parser + interpreter

lib/ast.ml

@@ -0,0 +1,37 @@
+type lisp_val = 
+  | LInt of int 
+  | LDouble of float 
+  | LCons of lisp_val * lisp_val
+  | LNil
+  | LSymbol of string
+  | LString of string
+  
+  (* a builtin function is expressed as a name and the ocaml function
+  that performs the operation. The function should take a list of arguments.
+  generally, builtin functions should handle their arguments directly,
+  and eval forms in the environment as necessary. *)
+  | LBuiltinFunction of string * (environment -> lisp_val -> lisp_val)
+  (* a function is a name, a parameter list, and function body. *)
+  | LFunction of string * lisp_val * lisp_val
+  | LQuoted of lisp_val
+and environment = (string, lisp_val) Hashtbl.t list
+
+
+let rec dbg_print_one v =
+  let pf = Printf.sprintf in
+  match v with
+  | LInt x ->  pf "<int: %d>" x
+  | LSymbol s -> pf "<symbol: '%s'>" s
+  | LString s -> pf "<string: '%s'>" s
+  | LNil -> pf "()"
+  | LCons (a, b) -> pf "(%s . %s)" (dbg_print_one a) (dbg_print_one b)
+  | LDouble d -> pf "<double: %f>" d
+  | LBuiltinFunction (name, _) -> pf "<builtin: %s>" name
+  | LFunction (name, args, _) -> pf "<function: '%s' lambda-list: %s>" 
+    name ((dbg_print_one args))
+  | LQuoted v -> pf "<quote: %s>" (dbg_print_one v)
+  (*| _ -> "<Something else>"*)
+
+let dbg_print_all vs =
+  let pr v = Printf.printf "%s\n" (dbg_print_one v) in
+  List.iter pr vs