diff --git a/src/lexer.rs b/src/lexer.rs
new file mode 100644
index 0000000..49db092
--- /dev/null
+++ b/src/lexer.rs
@@ -0,0 +1,179 @@
+
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub enum LTIRToken {
+    Symbol( String ),
+    Char( char ),
+    Num( i64 ),
+
+    // SingleQuote(String),
+    // DoubleQuote(String),
+    // TripleQuote(String),
+
+    ExprOpen,
+    ExprClose,
+
+    BlockOpen,
+    BlockClose,
+    StatementSep,
+}
+
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub enum LexError {
+    InvalidDigit,
+    InvalidChar
+}
+
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub enum LexerState {
+    Any,
+    Sym( String ),
+    Num( i64 ),
+    Char( Option<char> )
+}
+
+impl LexerState {
+    fn into_token(self) -> Option< LTIRToken > {
+        match self {
+            LexerState::Any => None,
+            LexerState::Sym(s) => Some(LTIRToken::Symbol(s)),
+            LexerState::Num(n) => Some(LTIRToken::Num(n)),
+            LexerState::Char(c) => Some(LTIRToken::Char(c?))
+        }
+    }
+}
+
+
+pub struct LTIRLexer<It>
+where It: std::iter::Iterator<Item = char>
+{
+    chars: std::iter::Peekable<It>,
+}
+
+impl<It> LTIRLexer<It>
+where It: Iterator<Item = char>
+{
+    pub fn into_inner(self) -> std::iter::Peekable<It> {
+        self.chars
+    }
+}
+
+impl<It> From<It> for LTIRLexer<It>
+where It: Iterator<Item = char>
+{
+    fn from(chars: It) -> Self {
+        LTIRLexer {
+            chars: chars.peekable()
+        }
+    }
+}
+
+impl<It> Iterator for LTIRLexer<It>
+where It: Iterator<Item = char>
+{
+    type Item = Result<LTIRToken, LexError>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let mut state = LexerState::Any;
+
+        while let Some(c) = self.chars.peek() {
+            match &mut state {
+
+                // determine token type
+                LexerState::Any => {
+                    match c {
+                        '(' => { self.chars.next(); return Some(Ok(LTIRToken::ExprOpen)); },
+                        ')' => { self.chars.next(); return Some(Ok(LTIRToken::ExprClose)); },
+                        '{' => { self.chars.next(); return Some(Ok(LTIRToken::BlockOpen)); },
+                        '}' => { self.chars.next(); return Some(Ok(LTIRToken::BlockClose)); },
+                        ';' => { self.chars.next(); return Some(Ok(LTIRToken::StatementSep)); },
+                        '\'' => { self.chars.next(); state = LexerState::Char(None); },
+                        c => {
+                            if c.is_whitespace() {
+                                self.chars.next();
+                            } else if c.is_digit(10) {
+                                state = LexerState::Num( 0 );
+                            } else {
+                                state = LexerState::Sym( String::new() );
+                            }
+                        }
+                    }
+                }
+
+                LexerState::Char(val) => {
+                    *val = Some(
+                        match self.chars.next() {
+                            Some('\\') => {
+                                match self.chars.next() {
+                                    Some('0') => '\0',
+                                    Some('n') => '\n',
+                                    Some('t') => '\t',
+                                    Some(c) => c,
+                                    None => {
+                                        return Some(Err(LexError::InvalidChar));
+                                    }
+                                }
+                            }
+                            Some(c) => c,
+                            None => {
+                                return Some(Err(LexError::InvalidChar));
+                            }
+                        });
+
+                    match self.chars.next() {
+                        Some('\'') => {
+                            if let Some(token) = state.clone().into_token() {
+                                return Some(Ok(token));
+                            }                            
+                        }
+                        _ => {
+                            return Some(Err(LexError::InvalidChar));
+                        }
+                    }
+                }
+
+                _ => {
+
+                    if c.is_whitespace()
+                        || *c == '(' || *c == ')'
+                        || *c == '{' || *c == '}'
+                        || *c == ';'
+                    {
+                        // finish the current token
+
+                        if let Some(token) = state.clone().into_token() {
+                            return Some(Ok(token));
+                        }
+                    } else {
+                        // append to the current token
+
+                        let c = self.chars.next().unwrap();
+
+                        match &mut state {
+                            LexerState::Sym(s) => {
+                                s.push(c);
+                            }
+
+                            LexerState::Num(n) => {
+                                if let Some(d) = c.to_digit(10) {
+                                    *n = (*n) * 10 + d as i64;
+                                } else {
+                                    return Some(Err(LexError::InvalidDigit));
+                                }
+                            }
+
+                            _ => {}
+                        }
+                    }
+                }
+            }
+        }
+
+        if let Some(token) = state.into_token() {
+            Some(Ok(token))
+        } else {
+            None
+        }
+    }
+}
+
+
diff --git a/src/main.rs b/src/main.rs
index 794d7c9..6194e6e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -8,6 +8,8 @@ mod expr;
 mod symbols;
 mod procedure_compiler;
 mod runtime;
+mod lexer;
+mod parser;
 
 use crate::{
     expr::{LTExpr, Statement},
@@ -15,6 +17,10 @@ use crate::{
     procedure_compiler::ProcedureCompiler
 };
 
+
+/*
+*/
+
 fn main() {
     // create virtual machine with 4096 words of memory
     let mut vm = tisc::VM::new(0x1000);
@@ -25,6 +31,25 @@ fn main() {
 
     let typectx = main_scope.read().unwrap().typectx.clone();
 
+
+    let mut lexer = lexer::LTIRLexer::from(
+        "{
+            emit '*';
+
+            let x : ℤ_2^64~machine::UInt64~machine::Word = 8;
+            while (i< x 7) {
+                = x (i+ x 1);
+            }
+
+            let square = (
+                (λ x (i* x x))
+            )
+        }".chars()
+    );
+
+    let block = parser::parse_block( &mut lexer.peekable() );
+    eprintln!("parsed block = {:?}", block);
+
     /* define type of the symbol
      */
     main_scope.write().unwrap()
diff --git a/src/parser.rs b/src/parser.rs
new file mode 100644
index 0000000..ffeb44d
--- /dev/null
+++ b/src/parser.rs
@@ -0,0 +1,73 @@
+use {
+    std::iter::Peekable,
+    crate::{
+        lexer::{LTIRLexer, LTIRToken, LexError},
+        expr::LTExpr
+    }
+};
+
+#[derive(Clone, Debug)]
+pub enum ParseError {
+    LexError(LexError),
+    UnexpectedClose,
+    UnexpectedEnd,
+    UnexpectedToken
+}
+
+pub fn parse_statement<It>(
+    tokens: &mut Peekable<LTIRLexer<It>>
+) -> Result< crate::expr::Statement, ParseError >
+where It: Iterator<Item = char>
+{
+    Err(ParseError::UnexpectedEnd)
+}
+
+pub fn parse_block<It>(
+    tokens: &mut Peekable<LTIRLexer<It>>
+) -> Result< crate::expr::LTExpr, ParseError >
+where It: Iterator<Item = char>
+{
+    Err(ParseError::UnexpectedEnd)
+}
+
+pub fn parse_expr<It>(
+    tokens: &mut Peekable<LTIRLexer<It>>
+) -> Result< crate::expr::LTExpr, ParseError >
+where It: Iterator<Item = char>
+{
+    let mut children = Vec::new();
+
+    match tokens.next() {
+        Some(Ok(LTIRToken::ExprOpen)) => {
+            if let Ok(subexpr) = parse_expr( tokens ) {
+                
+            } else {
+                
+            }
+/*
+            Err(ParseError::UnexpectedEnd)
+        */
+        },
+        Some(Ok(LTIRToken::BlockOpen)) => {
+            /*
+            Err(ParseError::UnexpectedEnd)
+            */
+        }
+        /*
+        _ => Err(ParseError::UnexpectedToken),
+        None => Err(ParseError::UnexpectedEnd)
+        */
+        _ => {}
+    }
+
+    if children.len() > 0 {
+        let head = children.remove(0);
+        Ok(LTExpr::Application {
+            head: Box::new(head),
+            body: children
+        })
+    } else {
+        Err(ParseError::UnexpectedEnd)
+    }
+}
+