TigerインタプリタでUnitを扱いたい

code:diff

diff --git a/bin/main.ml b/bin/main.ml

index d54652e..c2ad7d7 100644

--- a/bin/main.ml

+++ b/bin/main.ml

@@ -14,8 +14,7 @@ let () =

match args with

print_string s;

- (* NOTE: 本当は unit を返したいけどまだ未実装なので 0 を返してる *)

- Tiger.Eval.IntVal(0)

+ Tiger.Eval.UnitVal

| _ -> failwith "invalid arguments"

))

] in

diff --git a/lib/eval.ml b/lib/eval.ml

index d759c21..e1d7083 100644

--- a/lib/eval.ml

+++ b/lib/eval.ml

@@ -3,6 +3,7 @@ and table = (id * val_t) list

and val_t =

IntVal of int

| StringVal of string

+ | UnitVal

| FunctionDec of id list * Syntax.t

| BuiltInFunction of (val_t list -> table -> val_t)

@@ -10,6 +11,7 @@ let rec f expr env: val_t * table =

match expr with

| Syntax.IntExp n -> (IntVal n, env)

| Syntax.StringExp s -> (StringVal s, env)

+ | Syntax.UnitExp -> (UnitVal, env)

| Syntax.VarExp s -> (List.assoc s env, env)

| Syntax.LetExp { decs; body } ->

let new_env = List.fold_left

@@ -24,7 +26,7 @@ let rec f expr env: val_t * table =

| IntVal 0 ->

(match else' with

| Some else' -> f else' env

- | None -> (IntVal 0, env))

+ | None -> (UnitVal, env))

| _ -> failwith "type error")

| Syntax.CallExp { id; args } ->

(let func = List.assoc id env in

@@ -103,6 +105,7 @@ and string_of_val v =

match v with

IntVal n -> string_of_int n

| StringVal s -> s

+ | UnitVal -> "()"

| FunctionDec _ -> "<fun>"

| BuiltInFunction _ -> "<builtin>"

diff --git a/lib/parser.mly b/lib/parser.mly

index 4040da7..32f4a41 100644

--- a/lib/parser.mly

+++ b/lib/parser.mly

@@ -40,6 +40,7 @@ program: exp EOF { $1 }

exp:

INT { Syntax.IntExp($1) }

| STRING { Syntax.StringExp($1) }

+| LPAREN RPAREN { Syntax.UnitExp }

| ID { Syntax.VarExp($1) }

| LPAREN exp RPAREN { $2 }

| exp PLUS exp { Syntax.OpExp { left = $1; op = Syntax.PlusOp; right = $3} }

diff --git a/lib/syntax.ml b/lib/syntax.ml

index fdbabc8..4ce1f99 100644

--- a/lib/syntax.ml

+++ b/lib/syntax.ml

@@ -15,6 +15,7 @@ and op_t =

and t =

| IntExp of int (* 整数 *)

| StringExp of string (* 文字列 *)

+ | UnitExp (* ユニット *)

| LetExp of { decs: dec_t list; body: t }

| VarExp of string

| CallExp of { id: string; args: t list } (* 関数呼び出し *)

diff --git a/test/tiger_test.ml b/test/tiger_test.ml

index ea6f020..2a32255 100644

--- a/test/tiger_test.ml

+++ b/test/tiger_test.ml

@@ -12,8 +12,7 @@ let eval src =

match args with

print_string s;

- (* NOTE: 本当は unit を返したいけどまだ未実装なので 0 を返してる *)

- Tiger.Eval.IntVal(0)

+ Tiger.Eval.UnitVal

| _ -> failwith "invalid arguments"

))

]