unikernel/duniverse/dune_/doc/tutorials/developing-with-dune/introduction/ast.ml

@@ -0,0 +1,3 @@
+type exp =
+  | Int of int
+  | Add of exp * exp

unikernel/duniverse/dune_/doc/tutorials/developing-with-dune/introduction/calc.ml

@@ -0,0 +1,9 @@
+let rec eval = function Ast.Int n -> n | Add (a, b) -> eval a + eval b
+
+let () =
+  while true do
+    Printf.printf ">> %!";
+    let lb = Lexing.from_channel Stdlib.stdin in
+    let e = Parser.main Lexer.token lb in
+    Printf.printf "%d\n" (eval e)
+  done

unikernel/duniverse/dune_/doc/tutorials/developing-with-dune/introduction/dune

@@ -0,0 +1,7 @@
+(executable
+ (public_name calc))
+
+(ocamllex lexer)
+
+(menhir
+ (modules parser))

unikernel/duniverse/dune_/doc/tutorials/developing-with-dune/introduction/dune-project

@@ -0,0 +1,3 @@
+(lang dune 3.18)
+(using menhir 3.0)
+(package (name calc))

unikernel/duniverse/dune_/doc/tutorials/developing-with-dune/introduction/lexer.mll

@@ -0,0 +1,10 @@
+let space = [' ']+
+
+let digit = ['0'-'9']
+
+rule token = parse
+    | eof { Parser.Eof }
+    | space { token lexbuf }
+    | '\n' { Parser.Eof }
+    | '+' { Parser.Plus }
+    | digit+ { Parser.Int (int_of_string (Lexing.lexeme lexbuf)) }

unikernel/duniverse/dune_/doc/tutorials/developing-with-dune/introduction/parser.mly

@@ -0,0 +1,18 @@
+%token Eof
+%token<int> Int
+%token Plus
+%start<Ast.exp> main
+
+%left Plus
+
+%{ open Ast %}
+
+%%
+
+main: expr Eof { $1 }
+
+expr:
+| Int { Int $1 }
+| expr Plus expr { Add ($1, $3) }
+
+%%