fallible wip1

src/ast/ast.rs

@@ -2,11 +2,13 @@ use std::fmt;
 
 // ast
 
+pub type Id = String;
+
 // println!("{:?}", ..)
 #[derive(Debug)]
 pub enum NumOrId {
-    Num(usize),
-    Id(String),
+    Num(i32),
+    Id(Id),
 }
 
 // println!("{}", ..)
@@ -19,3 +21,11 @@ impl fmt::Display for NumOrId {
         Ok(())
     }
 }
+
+pub type Stmts = Vec<Stmt>;
+
+#[derive(Debug)]
+pub enum Stmt {
+    Let(Id, NumOrId),
+    If(Id, Stmts, Option<Stmts>),
+}

src/ast/main.rs

@@ -5,6 +5,7 @@ lalrpop_mod!(pub parser, "/ast/parser.rs");
 use parser::*;
 
 pub mod ast;
+use ast::*;
 
 fn main() {
     println!("minimal");
@@ -26,3 +27,29 @@ fn parse_num_or_id() {
         "a1_a"
     );
 }
+
+type Error = String;
+
+fn type_check(stmts: &Stmts) -> Result<(), Error> {
+    for i in stmts {
+        match i {
+            Stmt::Let(_, _) => {
+                println!("let");
+            }
+            Stmt::If(_, _, __) => {
+                println!("if");
+            }
+        }
+    }
+    Ok(())
+}
+
+#[test]
+fn test_stmts() {
+    let stmts = vec![
+        Stmt::Let("a".to_string(), NumOrId::Num(1)),
+        Stmt::Let("b".to_string(), NumOrId::Num(2)),
+        Stmt::Let("c".to_string(), NumOrId::Num(3)),
+    ];
+    type_check(&stmts).unwrap();
+}

src/ast/parser.lalrpop

@@ -9,8 +9,8 @@ pub NumOrId: NumOrId = {
     Id => NumOrId::Id(<>),
 }
  
-pub Num: usize = {
-    r"[0-9]+" => usize::from_str(<>).unwrap(),
+pub Num: i32 = {
+    r"[0-9]+" => i32::from_str(<>).unwrap(),
 };
 
 pub Id: String = {