Added REPL

src/cli/mod.rs

@@ -0,0 +1,39 @@
+use std::io;
+use std::io::Write;
+
+use crate::types::TokenType;
+use crate::lexer::def;
+
+pub fn start() {
+    const PROMPT: &'static str = ">> ";
+
+    greet();
+
+    loop {
+        print!("{}", PROMPT);
+
+        let _ = io::stdout().flush();
+
+        let mut input = String::new();
+
+        io::stdin()
+          .read_line(&mut input)
+          .expect("Failed to read line");
+
+
+        let mut lex = def::new_lexer(&input);
+        loop {
+            let tok = lex.next();
+            match tok.ttype {
+                TokenType::EOF => break,
+                _ => {
+                    println!("{:?}", tok);
+                }
+            }
+        }
+    }
+}
+
+fn greet() {
+    println!("Hello there! This is the Hi Repl");
+}

src/lib.rs

@@ -1,2 +1,3 @@
 pub mod lexer;
 pub mod types;
+pub mod cli;

src/main.rs

@@ -1,5 +1,5 @@
-use hi::lexer;
+use hi::cli;
 
 fn main() {
-    lexer::sanket();
+    cli::start();
 }

src/types/mod.rs

@@ -51,6 +51,7 @@ pub struct Lexer <'a> {
     pub ch: u8
 }
 
+#[derive(Debug)]
 pub struct Token {
     pub ttype: TokenType,
     pub literal: String 
@@ -79,12 +80,8 @@ impl Lexer <'_> {
                   _    => new_token(TokenType::ASSIGN, tok)
                 }
             },
-            b'+' => new_token(
-              TokenType::PLUS,
-              tok),
-            b'-' => new_token(
-              TokenType::MINUS,
-              tok),
+            b'+' => new_token(TokenType::PLUS, tok),
+            b'-' => new_token(TokenType::MINUS, tok),
             b'!' => {
                 match self.peek() {
                   b'=' => {
@@ -94,39 +91,17 @@ impl Lexer <'_> {
                   _    => new_token(TokenType::BANG, tok)
                 }
             },
-            b'/' => new_token(
-              TokenType::SLASH,
-              tok),
-            b'*' => new_token(
-              TokenType::ASTERISK,
-              tok),
-            b'<' => new_token(
-              TokenType::LT,
-              tok),
-            b'>' => new_token(
-              TokenType::GT,
-              tok),
-            b';' => new_token(
-              TokenType::SEMICOLON,
-              tok),
-            b'(' => new_token(
-              TokenType::LPAREN,
-              tok),
-            b')' => new_token(
-              TokenType::RPAREN,
-              tok),
-            b',' => new_token(
-              TokenType::COMMA,
-              tok),
-            b'{' => new_token(
-              TokenType::LBRACE,
-              tok),
-            b'}' => new_token(
-              TokenType::RBRACE,
-              tok),
-            0    => new_token(
-              TokenType::EOF,
-              String::from("")),
+            b'/' => new_token(TokenType::SLASH, tok),
+            b'*' => new_token(TokenType::ASTERISK, tok),
+            b'<' => new_token(TokenType::LT, tok),
+            b'>' => new_token(TokenType::GT, tok),
+            b';' => new_token(TokenType::SEMICOLON, tok),
+            b'(' => new_token(TokenType::LPAREN, tok),
+            b')' => new_token(TokenType::RPAREN, tok),
+            b',' => new_token(TokenType::COMMA, tok),
+            b'{' => new_token(TokenType::LBRACE, tok),
+            b'}' => new_token(TokenType::RBRACE, tok),
+            0    => new_token(TokenType::EOF, String::from("")),
             _    => {
                 if helpers::is_letter(self.ch) {
                     let ident = self.read_identifier();
@@ -138,7 +113,8 @@ impl Lexer <'_> {
 
                 }
 
-                return new_token(TokenType::ILLEGAL, self.ch.to_string());
+                self.read_char();
+                return new_token(TokenType::ILLEGAL, tok);
             }
         };