clippy fix

src/builtin_cells.rs

@@ -1,4 +1,4 @@
-use crate::frontend::types::{Type, TypeStruct};
+use crate::frontend::types::TypeStruct;
 use crate::frontend::Callable;
 use crate::rtlil;
 use crate::rtlil::SigSpec;
@@ -39,7 +39,7 @@ fn instantiate_binop(celltype: &str, id: &str, args: &[SigSpec], ret: &SigSpec)
     cell
 }
 
-fn make_binop_callable<'ctx>(name: &str, celltype: &'static str) -> Callable<'ctx> {
+fn make_binop_callable<'ctx>(name: &str, _celltype: &'static str) -> Callable<'ctx> {
     // FIXME: CRIMES CRIMES CRIMES
     let logic_type: &'static TypeStruct = Box::leak(Box::new(TypeStruct::logic_infer()));
     let args = vec![
@@ -53,7 +53,7 @@ fn make_binop_callable<'ctx>(name: &str, celltype: &'static str) -> Callable<'ct
     }
 }
 
-fn make_unnop_callable<'ctx>(name: &str, celltype: &'static str) -> Callable<'ctx> {
+fn make_unnop_callable<'ctx>(name: &str, _celltype: &'static str) -> Callable<'ctx> {
     // FIXME: CRIMES CRIMES CRIMES
     let logic_type: &'static TypeStruct = Box::leak(Box::new(TypeStruct::logic_infer()));
     let args = vec![(Some("A".to_owned()), logic_type)];

src/frontend.rs

@@ -8,8 +8,8 @@ pub use callable::Callable;
 pub use types::{Type, TypeStruct};
 
 mod callable;
-pub mod types;
 pub mod typed_ir;
+pub mod types;
 
 /// lots of code is still not width-aware, this constant keeps track of that
 const TODO_WIDTH: u32 = 1;
@@ -255,7 +255,7 @@ fn lower_expression(
                 }));
             }
 
-            let cell_id = module.make_genid(&callable.name());
+            let cell_id = module.make_genid(callable.name());
 
             let output_gen_id = format!("{}$out", &cell_id);
             module.add_wire(rtlil::Wire::new(&output_gen_id, TODO_WIDTH, None));
@@ -316,11 +316,7 @@ pub fn lower_module(pa_module: parser::Module) -> Result<String, CompileError> {
             parser::PortDirection::Input => rtlil::PortOption::Input(idx as i32 + 1),
             parser::PortDirection::Output => rtlil::PortOption::Output(idx as i32 + 1),
         };
-        let wire = rtlil::Wire::new(
-            sig.il_id.to_owned(),
-            TODO_WIDTH,
-            Some(dir_option),
-        );
+        let wire = rtlil::Wire::new(sig.il_id.to_owned(), TODO_WIDTH, Some(dir_option));
         ir_module.add_wire(wire);
     }
     for item in pa_module.items {

src/frontend/typed_ir.rs

@@ -9,8 +9,7 @@ struct Element<'ty> {
 
 struct Signal<'ty> {
     pub id: u32,
-    pub typ: Type<'ty>
+    pub typ: Type<'ty>,
 }
 
-struct Expression {
-}
+struct Expression {}

src/main.rs

@@ -9,8 +9,6 @@ use std::io::prelude::*;
 use std::path::PathBuf;
 
 use structopt::StructOpt;
-use nom_greedyerror::convert_error;
-use ariadne::Source;
 
 #[derive(Debug, StructOpt)]
 #[structopt(name = "example", about = "An example of StructOpt usage.")]
@@ -42,12 +40,21 @@ fn main() {
         .expect("error reading file");
     let input: &str = input.as_str();
     let input = parser::Span::new(input);
-    let parsed = parser::parse(input);
+    let lexed = parser::tokens::lex(input).unwrap();
+    let tokens = parser::tokens::TokenSpan::new(&lexed.1);
+    let parsed = parser::parse(tokens);
     match parsed {
         Err(nom::Err::Error(err) | nom::Err::Failure(err)) => {
-            parser::error::convert_error(input, err).eprint(Source::from(input.fragment())).unwrap();
+            if opt.debug {
+                println!("{err:#?}");
+            }
+            /*
+            parser::error::convert_error(input, err)
+                .eprint(Source::from(input.fragment()))
+                .unwrap();
+            */
         }
-        Err(_) => ( unreachable!() ),
+        Err(_) => (unreachable!()),
         Ok(res) => {
             if opt.debug {
                 println!("{:#?}", res);

src/parser.rs

@@ -1,16 +1,17 @@
+pub mod error;
+mod literals;
 pub mod module;
 pub mod proc;
-mod literals;
-pub mod error;
+pub mod tokens;
 
 use nom::{
     branch::alt,
     bytes::complete::tag,
-    character::complete::{alpha1, alphanumeric1, char, multispace0, u64 as decimal},
+    character::complete::{alpha1, alphanumeric1, multispace0},
     combinator::{map, opt, recognize},
-    error::{ParseError, ErrorKind},
+    error::{ErrorKind, ParseError},
     multi::{many0, separated_list0},
-    sequence::{delimited, pair, preceded, separated_pair, terminated, tuple},
+    sequence::{delimited, pair, preceded, separated_pair, tuple},
 };
 use nom_greedyerror::GreedyError;
 use nom_locate::LocatedSpan;
@@ -22,8 +23,8 @@ pub type IErr<I> = GreedyError<I, ErrorKind>;
 // custom IResult type for VerboseError
 pub type IResult<I, O, E = IErr<I>> = nom::IResult<I, O, E>;
 
-use literals::hexadecimal;
 pub use crate::parser::module::{module, Module, ModuleItem, PortDirection};
+use crate::parser::tokens::{token, TokenKind as tk, TokenSpan};
 
 fn ws0<'a, F: 'a, O, E: ParseError<Span<'a>>>(
     inner: F,
@@ -42,29 +43,20 @@ fn identifier(input: Span) -> IResult<Span, Span> {
 }
 
 // TODO: allow recursive generics
-fn typename(input: Span) -> IResult<Span, TypeName> {
+// TODO: allow expressions again
+fn typename(input: TokenSpan) -> IResult<TokenSpan, TypeName> {
     map(
         tuple((
-            identifier,
-            opt(delimited(char('<'), ws0(expression), char('>')))
+            token(tk::Ident),
+            opt(delimited(token(tk::LAngle), expression, token(tk::RAngle))),
         )),
-        |(ident, _)| {
-            TypeName {
-                name: ident,
-                generics: ()
-            }
-        }
+        |(ident, _)| TypeName {
+            name: ident.span(),
+            generics: (),
+        },
     )(input)
 }
 
-fn widthspec(input: Span) -> IResult<Span, u64> {
-    delimited(char('['), ws0(decimal), char(']'))(input)
-}
-
-fn intliteral(input: Span) -> IResult<Span, (u64, u64)> {
-    tuple((terminated(decimal, char('\'')), alt((decimal, hexadecimal))))(input)
-}
-
 #[derive(Debug)]
 pub struct TypeName<'a> {
     name: Span<'a>,
@@ -75,7 +67,7 @@ pub struct TypeName<'a> {
 pub struct NetDecl<'a> {
     pub name: Span<'a>,
     pub typ: TypeName<'a>,
-    pub value: Option<(u64, u64)>,
+    pub value: Option<Span<'a>>,
 }
 
 #[derive(Debug)]
@@ -115,87 +107,91 @@ pub enum Expression<'a> {
     Operation(Box<Operation<'a>>),
 }
 
-fn declaration(i: Span) -> IResult<Span, NetDecl> {
+// TODO: reallow assignments
+fn declaration(i: TokenSpan) -> IResult<TokenSpan, NetDecl> {
     map(
         tuple((
-            separated_pair(identifier, ws0(char(':')), typename),
-            opt(preceded(ws0(char('=')), intliteral)),
+            separated_pair(token(tk::Ident), token(tk::Colon), typename),
+            opt(preceded(token(tk::Assign), token(tk::Number))),
         )),
-        |((ident, typ), value)| NetDecl {
-            name: ident,
+        |((ident, typ), _value)| NetDecl {
+            name: ident.span(),
             typ,
-            value,
+            value: None,
         },
     )(i)
 }
 
-fn operation(input: Span) -> IResult<Span, Operation> {
+fn operation(input: TokenSpan) -> IResult<TokenSpan, Operation> {
     // temporarily given up on before I learn the shunting yard algorithm
     alt((
         map(
-            separated_pair(ws0(expression_nonrecurse), char('&'), ws0(expression)),
+            separated_pair(expression_nonrecurse, token(tk::BitAnd), expression),
             |(a, b)| Operation::And { a, b },
         ),
         map(
-            separated_pair(ws0(expression_nonrecurse), char('|'), ws0(expression)),
+            separated_pair(expression_nonrecurse, token(tk::BitOr), expression),
             |(a, b)| Operation::Or { a, b },
         ),
         map(
-            separated_pair(ws0(expression_nonrecurse), char('^'), ws0(expression)),
+            separated_pair(expression_nonrecurse, token(tk::BitXor), expression),
             |(a, b)| Operation::Xor { a, b },
         ),
-        map(preceded(char('~'), expression), Operation::Not),
+        map(preceded(token(tk::BitNot), expression), Operation::Not),
     ))(input)
 }
 
-fn call_item(input: Span) -> IResult<Span, Call> {
+fn call_item(input: TokenSpan) -> IResult<TokenSpan, Call> {
     map(
         tuple((
-            ws0(identifier),
+            token(tk::Ident),
             delimited(
-                char('('),
-                ws0(separated_list0(char(','), expression)),
-                char(')'),
+                token(tk::LParen),
+                separated_list0(token(tk::Comma), expression),
+                token(tk::RParen),
             ),
         )),
-        |(name, args)| Call { name, args },
+        |(name, args)| Call {
+            name: name.span(),
+            args,
+        },
     )(input)
 }
 
 /// parser combinators can not parse left-recursive grammars. To work around this, we split
 /// expressions into a recursive and non-recursive portion.
 /// Parsers reachable from this point must call expression_nonrecurse instead
-fn expression(input: Span) -> IResult<Span, Expression> {
+fn expression(input: TokenSpan) -> IResult<TokenSpan, Expression> {
     alt((
-        map(ws0(operation), |op| Expression::Operation(Box::new(op))),
+        map(operation, |op| Expression::Operation(Box::new(op))),
         expression_nonrecurse,
     ))(input)
 }
 
 /// the portion of the expression grammar that can be parsed without left recursion
-fn expression_nonrecurse(input: Span) -> IResult<Span, Expression> {
+fn expression_nonrecurse(input: TokenSpan) -> IResult<TokenSpan, Expression> {
     alt((
-        map(ws0(decimal), Expression::Literal),
-        map(ws0(call_item), |call| Expression::Call(Box::new(call))),
-        map(ws0(identifier), |ident| {
-            Expression::Ident(*ident.fragment())
+        map(token(tk::Number), |_| Expression::Literal(42)),
+        map(call_item, |call| Expression::Call(Box::new(call))),
+        map(token(tk::Ident), |ident| {
+            Expression::Ident(*ident.span().fragment())
         }),
-        delimited(char('('), expression, char(')')),
+        delimited(token(tk::LParen), expression, token(tk::RParen)),
     ))(input)
 }
 
-fn assign_statement(input: Span) -> IResult<Span, Assign> {
+fn assign_statement(input: TokenSpan) -> IResult<TokenSpan, Assign> {
     map(
-        separated_pair(ws0(identifier), char('='), ws0(expression)),
+        separated_pair(token(tk::Ident), token(tk::EqAssign), expression),
         |(lhs, expr)| Assign {
-            lhs: (*lhs.fragment()),
+            lhs: (*lhs.span().fragment()),
             expr,
         },
     )(input)
 }
 
-pub fn parse(input: Span) -> IResult<Span, Module> {
-    ws0(module)(input)
+pub fn parse(input: TokenSpan) -> IResult<TokenSpan, Module> {
+    module(input)
 }
 
 #[cfg(test)]

src/parser/error.rs

@@ -1,36 +1,26 @@
-use std::fmt::Debug;
-use std::ops::Deref;
-
-use super::{Span, IErr};
-use nom::error::ErrorKind;
-use nom_greedyerror::{Position, GreedyErrorKind};
-use ariadne::{Report, ReportKind, Label};
+use super::{IErr, Span};
+use ariadne::{Label, Report, ReportKind};
+use nom_greedyerror::{GreedyErrorKind, Position};
 
 fn span_to_range(input: Span) -> std::ops::Range<usize> {
     input.position()..(input.position() + input.len())
 }
 
-pub fn convert_error(
-    input: Span, 
-    e: IErr<Span>,
-) -> Report {
+pub fn convert_error(_input: Span, e: IErr<Span>) -> Report {
     let mut labels = Vec::new();
     for err in e.errors {
         let label = match err.1 {
             GreedyErrorKind::Context(ctx) => {
-                Label::new(span_to_range(err.0))
-                    .with_message(format!("in {ctx}"))
-            },
-            GreedyErrorKind::Char(c) => { 
-                Label::new(err.0.position()..err.0.position())
-                    .with_message(format!("expected {c:?}"))
-            },
-            GreedyErrorKind::Nom(_) => todo!(),
+                Label::new(span_to_range(err.0)).with_message(format!("in {ctx}"))
+            }
+            GreedyErrorKind::Char(c) => Label::new(err.0.position()..err.0.position())
+                .with_message(format!("expected {c:?}")),
+            GreedyErrorKind::Nom(kind) => Label::new(err.0.position()..err.0.position())
+                .with_message(format!("nom error {kind:?}")),
         };
         labels.push(label);
     }
-    let mut rep = Report::build(ReportKind::Error, (), 0)
-        .with_message("Parse Error");
+    let mut rep = Report::build(ReportKind::Error, (), 0).with_message("Parse Error");
     for lbl in labels {
         rep = rep.with_label(lbl)
     }

src/parser/literals.rs

@@ -17,7 +17,8 @@ pub fn hexadecimal(input: Span) -> IResult<Span, u64> {
             ))),
         ),
         |out: Span| {
-            u64::from_str_radix(&str::replace(out.fragment(), "_", ""), 16).expect("error parsing literal")
+            u64::from_str_radix(&str::replace(out.fragment(), "_", ""), 16)
+                .expect("error parsing literal")
         },
     )(input)
 }

src/parser/module.rs

@@ -1,17 +1,16 @@
 use nom::{
     branch::alt,
-    bytes::complete::tag,
-    character::complete::{char, multispace1},
-    combinator::{consumed, map},
+    combinator::map,
     error::context,
     multi::{many0, separated_list0},
-    sequence::{delimited, terminated, tuple, preceded},
+    sequence::{delimited, preceded, tuple},
 };
 
 use crate::parser::{
-    assign_statement, declaration, identifier,
+    assign_statement, declaration,
     proc::{proc_block, ProcBlock},
-    ws0, Assign, IResult, NetDecl, Span, typename
+    tokens::{token, TokenKind as tk, TokenSpan},
+    typename, Assign, IResult, NetDecl, Span,
 };
 
 #[derive(Debug)]
@@ -22,7 +21,6 @@ pub enum PortDirection {
 
 #[derive(Debug)]
 pub struct PortDecl<'a> {
-    pub pos: Span<'a>,
     pub direction: PortDirection,
     pub net: NetDecl<'a>,
 }
@@ -40,56 +38,45 @@ pub enum ModuleItem<'a> {
     Proc(ProcBlock<'a>),
 }
 
-fn port_decl(i: Span) -> IResult<Span, PortDecl> {
-    map(
-        consumed(
-            declaration,
-        ),
-        |(pos, net)| PortDecl {
-            pos,
-            direction: PortDirection::Input,
-            net,
-        },
-    )(i)
+fn port_decl(i: TokenSpan) -> IResult<TokenSpan, PortDecl> {
+    map(declaration, |net| PortDecl {
+        direction: PortDirection::Input,
+        net,
+    })(i)
 }
 
-fn inputs_list(input: Span) -> IResult<Span, Vec<PortDecl>> {
-    separated_list0(ws0(char(',')), ws0(port_decl))(input)
+fn inputs_list(input: TokenSpan) -> IResult<TokenSpan, Vec<PortDecl>> {
+    separated_list0(token(tk::Comma), port_decl)(input)
 }
 
-fn assign_item(input: Span) -> IResult<Span, Assign> {
+fn assign_item(input: TokenSpan) -> IResult<TokenSpan, Assign> {
     context(
         "assignment",
-        delimited(
-            ws0(terminated(tag("assign"), multispace1)),
-            ws0(assign_statement),
-            ws0(char(';')),
-        ),
+        delimited(token(tk::Assign), assign_statement, token(tk::Semicolon)),
     )(input)
 }
 
-fn module_item(input: Span) -> IResult<Span, ModuleItem> {
+fn module_item(input: TokenSpan) -> IResult<TokenSpan, ModuleItem> {
     alt((
         map(assign_item, ModuleItem::Assign),
         map(proc_block, ModuleItem::Proc),
     ))(input)
 }
 
-/// parse a top-level module declaration
-pub fn module(input: Span) -> IResult<Span, Module> {
+pub fn module(input: TokenSpan) -> IResult<TokenSpan, Module> {
     context(
         "module",
         map(
             tuple((
-                tag("module"),
-                ws0(identifier),
-                ws0(delimited(char('('), ws0(inputs_list), char(')'))),
-                ws0(preceded(tag("->"), ws0(typename))),
-                ws0(delimited(char('{'), ws0(many0(ws0(module_item))), char('}'))),
+                token(tk::Module),
+                token(tk::Ident),
+                delimited(token(tk::LParen), inputs_list, token(tk::RParen)),
+                preceded(token(tk::RArrow), typename),
+                delimited(token(tk::LBrace), many0(module_item), token(tk::RBrace)),
             )),
-            |(_, name, inputs, ret, items)| Module {
-                name,
-                // TODO: add back in returns
+            |(_, name, inputs, _ret, items)| Module {
+                // TODO: bring back returns
+                name: name.span(),
                 ports: inputs,
                 items,
             },

src/parser/proc.rs

@@ -1,7 +1,5 @@
 use nom::{
     branch::alt,
-    bytes::complete::tag,
-    character::complete::char,
     combinator::map,
     error::context,
     multi::{many1, separated_list1},
@@ -9,7 +7,9 @@ use nom::{
 };
 
 use crate::parser::{
-    assign_statement, expression, identifier, ws0, Assign, Expression, IResult, Span,
+    assign_statement, expression,
+    tokens::{token, TokenKind as tk, TokenSpan},
+    Assign, Expression, IResult, Span,
 };
 
 #[derive(Debug)]
@@ -36,38 +36,38 @@ pub struct MatchBlock<'a> {
     pub arms: Vec<(Expression<'a>, ProcStatement<'a>)>,
 }
 
-fn match_arm(input: Span) -> IResult<Span, (Expression, ProcStatement)> {
-    separated_pair(ws0(expression), tag("=>"), ws0(proc_statement))(input)
+fn match_arm(input: TokenSpan) -> IResult<TokenSpan, (Expression, ProcStatement)> {
+    separated_pair(expression, token(tk::FatArrow), proc_statement)(input)
 }
 
-fn match_block(input: Span) -> IResult<Span, MatchBlock> {
+fn match_block(input: TokenSpan) -> IResult<TokenSpan, MatchBlock> {
     context(
         "match block",
         map(
             tuple((
-                ws0(tag("match")),
-                ws0(delimited(char('('), ws0(expression), char(')'))),
-                ws0(delimited(
-                    char('{'),
-                    separated_list1(char(','), ws0(match_arm)),
-                    char('}'),
-                )),
+                token(tk::Match),
+                delimited(token(tk::LParen), expression, token(tk::RParen)),
+                delimited(
+                    token(tk::LBrace),
+                    separated_list1(token(tk::Comma), match_arm),
+                    token(tk::RBrace),
+                ),
             )),
             |(_, expr, arms)| MatchBlock { expr, arms },
         ),
     )(input)
 }
 
-fn statement_block(input: Span) -> IResult<Span, Vec<ProcStatement>> {
+fn statement_block(input: TokenSpan) -> IResult<TokenSpan, Vec<ProcStatement>> {
     delimited(
-        char('{'),
-        separated_list1(char(';'), ws0(proc_statement)),
-        char('}'),
+        token(tk::LBrace),
+        separated_list1(token(tk::Semicolon), proc_statement),
+        token(tk::RBrace),
     )(input)
 }
 
 /// parse a statement that is valid inside a proc block
-fn proc_statement(input: Span) -> IResult<Span, ProcStatement> {
+fn proc_statement(input: TokenSpan) -> IResult<TokenSpan, ProcStatement> {
     alt((
         map(match_block, ProcStatement::Match),
         map(statement_block, ProcStatement::Block),
@@ -75,16 +75,19 @@ fn proc_statement(input: Span) -> IResult<Span, ProcStatement> {
     ))(input)
 }
 
-pub fn proc_block(input: Span) -> IResult<Span, ProcBlock> {
+pub fn proc_block(input: TokenSpan) -> IResult<TokenSpan, ProcBlock> {
     context(
         "proc block",
         map(
             tuple((
-                ws0(tag("proc")),
-                ws0(delimited(char('('), ws0(identifier), char(')'))),
-                ws0(delimited(char('{'), many1(ws0(proc_statement)), char('}'))),
+                token(tk::Proc),
+                delimited(token(tk::LParen), token(tk::Ident), token(tk::RParen)),
+                delimited(token(tk::LBrace), many1(proc_statement), token(tk::RBrace)),
             )),
-            |(_, net, items)| ProcBlock { net, items },
+            |(_, net, items)| ProcBlock {
+                net: net.span(),
+                items,
+            },
         ),
     )(input)
 }

src/parser/tokens.rs

@@ -0,0 +1,208 @@
+//! convert text into a token stream
+
+use super::{identifier, ws0, IResult, Span};
+use nom::{
+    branch::alt,
+    bytes::complete::tag,
+    character::complete::{anychar, digit1},
+    combinator::{consumed, map, recognize},
+    error::ParseError,
+    multi::many0,
+};
+use std::fmt;
+
+pub struct Token<'a> {
+    span: Span<'a>,
+    kind: TokenKind,
+}
+
+impl fmt::Debug for Token<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "{:?} @{} {:?}",
+            self.kind,
+            self.span.location_offset(),
+            self.span.fragment()
+        )?;
+        Ok(())
+    }
+}
+
+impl<'a> Token<'a> {
+    fn new(span: Span<'a>, kind: TokenKind) -> Self {
+        Self { span, kind }
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
+}
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum TokenKind {
+    // no whitespace, for now
+    // no token trees either, for now
+    // Braces
+    LParen,
+    RParen,
+    LAngle,
+    RAngle,
+    LBrace,
+    RBrace,
+    LSquare,
+    RSquare,
+    // single chars
+    Colon,
+    Semicolon,
+    Comma,
+    BitNot,
+    BitAnd,
+    BitOr,
+    BitXor,
+    EqAssign,
+    // Multi Chars
+    FatArrow,
+    RArrow,
+    // Literals
+    Ident,
+    Number,
+    // Keywords
+    Module,
+    Assign,
+    Match,
+    Proc,
+    // Error
+    Error,
+}
+
+#[derive(Debug, Clone)]
+pub struct TokenSpan<'a> {
+    rest: &'a [Token<'a>],
+    pos: usize,
+}
+
+impl<'a> TokenSpan<'a> {
+    pub fn new(rest: &'a [Token<'a>]) -> Self {
+        Self { rest, pos: 0 }
+    }
+    pub fn with_pos(rest: &'a [Token<'a>], pos: usize) -> Self {
+        Self { rest, pos }
+    }
+}
+
+impl nom::InputTake for TokenSpan<'_> {
+    fn take(&self, count: usize) -> Self {
+        TokenSpan::with_pos(&self.rest[..count], self.pos + count)
+    }
+
+    fn take_split(&self, count: usize) -> (Self, Self) {
+        let (head, tail) = &self.rest.split_at(count);
+        (
+            TokenSpan::with_pos(head, self.pos),
+            TokenSpan::with_pos(tail, self.pos + count),
+        )
+    }
+}
+
+impl nom::InputLength for TokenSpan<'_> {
+    fn input_len(&self) -> usize {
+        self.rest.len()
+    }
+}
+
+impl nom_greedyerror::Position for TokenSpan<'_> {
+    fn position(&self) -> usize {
+        self.pos
+    }
+}
+
+/// combinator that matches a token kind
+pub fn token<'a, E>(
+    kind: TokenKind,
+) -> impl FnMut(TokenSpan<'a>) -> nom::IResult<TokenSpan, &Token, E>
+where
+    E: ParseError<TokenSpan<'a>>,
+{
+    move |input: TokenSpan| {
+        let next = &input.rest[0];
+        if next.kind == kind.clone() {
+            let rest = TokenSpan::with_pos(&input.rest[1..], input.pos + 1);
+            Ok((rest, next))
+        } else {
+            Err(nom::Err::Error(E::from_error_kind(
+                input,
+                // TODO: Proper errors here
+                nom::error::ErrorKind::Tag,
+            )))
+        }
+    }
+}
+
+pub fn lex(input: Span) -> IResult<Span, Vec<Token>> {
+    many0(ws0(alt((
+        lex_keywords,
+        lex_literals,
+        lex_braces,
+        lex_punctuation,
+        map(recognize(anychar), |span| {
+            Token::new(span, TokenKind::Error)
+        }),
+    ))))(input)
+}
+
+fn lex_braces(input: Span) -> IResult<Span, Token> {
+    map(
+        consumed(alt((
+            map(tag("("), |_| TokenKind::LParen),
+            map(tag(")"), |_| TokenKind::RParen),
+            map(tag("<"), |_| TokenKind::LAngle),
+            map(tag(">"), |_| TokenKind::RAngle),
+            map(tag("{"), |_| TokenKind::LBrace),
+            map(tag("}"), |_| TokenKind::RBrace),
+            map(tag("["), |_| TokenKind::LSquare),
+            map(tag("]"), |_| TokenKind::RSquare),
+        ))),
+        |(span, kind)| Token::new(span, kind),
+    )(input)
+}
+
+fn lex_literals(input: Span) -> IResult<Span, Token> {
+    map(
+        consumed(alt((
+            map(identifier, |_| TokenKind::Ident),
+            map(digit1, |_| TokenKind::Number),
+        ))),
+        |(span, kind)| Token::new(span, kind),
+    )(input)
+}
+
+fn lex_punctuation(input: Span) -> IResult<Span, Token> {
+    map(
+        consumed(alt((
+            map(tag(":"), |_| TokenKind::Colon),
+            map(tag(";"), |_| TokenKind::Semicolon),
+            map(tag(","), |_| TokenKind::Comma),
+            map(tag("->"), |_| TokenKind::RArrow),
+            map(tag("=>"), |_| TokenKind::FatArrow),
+            map(tag("~"), |_| TokenKind::BitNot),
+            map(tag("&"), |_| TokenKind::BitAnd),
+            map(tag("^"), |_| TokenKind::BitXor),
+            map(tag("|"), |_| TokenKind::BitOr),
+            map(tag("="), |_| TokenKind::EqAssign),
+        ))),
+        |(span, kind)| Token::new(span, kind),
+    )(input)
+}
+
+fn lex_keywords(input: Span) -> IResult<Span, Token> {
+    map(
+        consumed(alt((
+            map(tag("module"), |_| TokenKind::Module),
+            map(tag("assign"), |_| TokenKind::Assign),
+            map(tag("match"), |_| TokenKind::Match),
+            map(tag("proc"), |_| TokenKind::Proc),
+        ))),
+        |(span, kind)| Token::new(span, kind),
+    )(input)
+}