all errors now contain source location

crsn/src/asm/data/reg.rs

@@ -1,6 +1,8 @@
 use std::fmt::{self, Display, Formatter};
 
 use crate::asm::error::CrsnError;
+use sexp::SourcePosition;
+use crate::asm::patches::ErrWithPos;
 
 /// Register name
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
@@ -23,27 +25,27 @@ impl Display for Register {
     }
 }
 
-pub fn parse_reg(name: &str) -> anyhow::Result<Register> {
+pub fn parse_reg(name: &str, at: SourcePosition) -> Result<Register, CrsnError> {
     // TODO deduplicate code
     if let Some(rn) = name.strip_prefix("arg") {
         if rn.chars().find(|c: &char| !c.is_ascii_digit()).is_some() {
-            Err(CrsnError::Parse(format!("Bad register: {}", name).into()))?;
+            return Err(CrsnError::Parse(format!("Bad register: {}", name).into(), at))?;
         }
-        let val: u8 = rn.parse()?;
+        let val: u8 = rn.parse().err_pos(at)?;
         Ok(Register::Arg(val))
     } else if let Some(rn) = name.strip_prefix("res") {
         if rn.chars().find(|c: &char| !c.is_ascii_digit()).is_some() {
-            Err(CrsnError::Parse(format!("Bad register: {}", name).into()))?;
+            return Err(CrsnError::Parse(format!("Bad register: {}", name).into(), at))?;
         }
-        let val: u8 = rn.parse()?;
+        let val: u8 = rn.parse().err_pos(at)?;
         Ok(Register::Res(val))
     } else if let Some(rn) = name.strip_prefix("r") {
         if rn.chars().find(|c: &char| !c.is_ascii_digit()).is_some() {
-            Err(CrsnError::Parse(format!("Bad register: {}", name).into()))?;
+            return Err(CrsnError::Parse(format!("Bad register: {}", name).into(), at))?;
         }
-        let val: u8 = rn.parse()?;
+        let val: u8 = rn.parse().err_pos(at)?;
         Ok(Register::Gen(val))
     } else {
-        Err(CrsnError::Parse(format!("Bad reg name: {}", name).into()))?
+        Err(CrsnError::Parse(format!("Bad reg name: {}", name).into(), at))?
     }
 }

crsn/src/asm/error.rs

@@ -6,28 +6,20 @@ use thiserror::Error;
 use crate::asm::data::{Mask, Register};
 use crate::asm::data::literal::Label;
 use crate::asm::instr::Cond;
+use sexp::SourcePosition;
+use std::error::Error;
 
 /// csn_asm unified error type
 #[derive(Error, Debug)]
 pub enum CrsnError {
-    #[error("S-expression syntax error: {0:?}")]
+    #[error("S-expression parsing error: {0:?}")]
-    PreParse(#[from] Box<sexp::Error>),
+    Sexp(#[from] Box<sexp::Error>),
-    #[error("Parse error: {0:?}")]
+    #[error("Parse error: {0:?} at {1:?}")]
-    Parse(Cow<'static, str>),
+    Parse(Cow<'static, str>, SourcePosition),
-    #[error("Parse error in {1:?}: {0:?}")]
+    #[error("Parse error: {0:?} at {1:?}")]
-    ParseIn(Cow<'static, str>, sexp::Sexp),
+    ParseOther(Box<dyn Error + Send + Sync>, SourcePosition),
-    #[error("Assembler error: {0:?}")]
+    #[error("Assembler error: {0:?} at {1:?}")]
-    Asm(AsmError),
+    Asm(AsmError, SourcePosition),
-    #[error("Architecture error: {0:?}")]
-    Arch(ArchError),
-    #[error(transparent)]
-    Other(#[from] anyhow::Error),
-}
-
-impl From<std::num::ParseIntError> for CrsnError {
-    fn from(e: ParseIntError) -> Self {
-        CrsnError::Other(anyhow::anyhow!(e))
-    }
 }
 
 /// Error from the assembler stage (after parsing S-expressions and basic validation)
@@ -50,14 +42,3 @@ pub enum AsmError {
     #[error("Bad register type: {0}")]
     BadRegisterType(Register),
 }
-
-/// Architectural error - the code is syntactically OK, but cannot run
-#[derive(Error, Debug)]
-pub enum ArchError {
-    #[error("Register {0} does not exist")]
-    RegisterNotExist(Register),
-    #[error("Register {0} is not writable")]
-    RegisterNotWritable(Register),
-    #[error("Register {0} is not readable")]
-    RegisterNotReadable(Register),
-}

crsn/src/asm/instr/cond.rs

@@ -2,6 +2,7 @@ use std::fmt::{self, Display, Formatter};
 use std::ops::Not;
 
 use crate::asm::error::CrsnError;
+use sexp::SourcePosition;
 
 /// Condition flag
 #[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
@@ -45,7 +46,7 @@ pub enum Cond {
     NotCarry,
 }
 
-pub fn parse_cond(text: &str) -> Result<Cond, CrsnError> {
+pub fn parse_cond(text: &str, pos : SourcePosition) -> Result<Cond, CrsnError> {
     Ok(match text.trim_end_matches('?') {
         "eq" | "=" | "==" => Cond::Equal,
         "ne" | "<>" | "!=" | "≠" => Cond::NotEqual,
@@ -66,7 +67,7 @@ pub fn parse_cond(text: &str) -> Result<Cond, CrsnError> {
         "ov" | "^" => Cond::Overflow,
         "nov" | "!ov" | "!^" => Cond::NotOverflow,
         _ => {
-            return Err(CrsnError::Parse(format!("Unknown cond: {}", text).into()));
+            return Err(CrsnError::Parse(format!("Unknown cond: {}", text).into(), pos));
         }
     })
 }

crsn/src/asm/instr/flatten.rs

@@ -9,21 +9,33 @@ use crate::asm::instr::op::OpKind;
 use crate::builtin::defs::Barrier;
 use crate::builtin::defs::BuiltinOp;
 use std::fmt::Debug;
+use sexp::SourcePosition;
 
 /// A trait for something that can turn into multiple instructions
 pub trait Flatten : Debug {
     fn flatten(self: Box<Self>, label_num: &AtomicU32) -> Result<Vec<Op>, CrsnError>;
+
+    fn pos(&self) -> SourcePosition;
 }
 
 impl Flatten for () {
     fn flatten(self: Box<Self>, _label_num: &AtomicU32) -> Result<Vec<Op>, CrsnError> {
         Ok(vec![])
     }
+
+    fn pos(&self) -> SourcePosition {
+        SourcePosition::default()
+    }
 }
 
 impl Flatten for InstrWithBranches {
+    fn pos(&self) -> SourcePosition {
+        self.pos.clone()
+    }
+
     fn flatten(self: Box<Self>, label_num: &AtomicU32) -> Result<Vec<Op>, CrsnError> {
         let mut ops = vec![self.op];
+        let parent_pos = self.pos;
 
         if let Some(branches) = self.branches {
             let labels = HashMap::<Cond, u32>::new();
@@ -31,7 +43,7 @@ impl Flatten for InstrWithBranches {
             let end_lbl = Label::unique(label_num);
             for (cnt, (cond, branch)) in branches.into_iter().enumerate() {
                 if labels.contains_key(&cond) {
-                    return Err(CrsnError::Asm(AsmError::ConditionalAlreadyUsed(cond)));
+                    return Err(CrsnError::Asm(AsmError::ConditionalAlreadyUsed(cond), branch.pos()));
                 }
 
                 let next_lbl = if cnt == branch_count - 1 {
@@ -40,27 +52,29 @@ impl Flatten for InstrWithBranches {
                     Label::unique(label_num)
                 };
 
+                let pos = branch.pos().clone();
                 let mut flattened = branch.flatten(label_num)?;
 
                 if flattened.len() == 0 {
-                    ops.push(Op { cond: Some(cond), kind: BuiltinOp::Jump(end_lbl.clone()).into() });
+                    ops.push(Op { cond: Some(cond), pos: pos.clone(), kind: BuiltinOp::Jump(end_lbl.clone()).into() });
                 } else if flattened.len() == 1 && flattened[0].cond.is_none() && branch_count == 1 {
                     // optimization for single-branch conditionals with a single instruction
-                    ops.push(Op { cond: Some(cond), kind: flattened.remove(0).kind });
+                    ops.push(Op { cond: Some(cond), pos: pos.clone(), kind: flattened.remove(0).kind });
                 } else {
                     ops.push(Op {
                         kind: OpKind::BuiltIn(BuiltinOp::Jump(next_lbl.clone())),
+                        pos: pos.clone(),
                         cond: Some(!cond),
                     });
                     ops.extend(flattened);
                 }
 
                 if cnt != branch_count - 1 {
-                    ops.push(BuiltinOp::Jump(end_lbl.clone()).into());
+                    ops.push(BuiltinOp::Jump(end_lbl.clone()).into_op(pos.clone()));
-                    ops.push(BuiltinOp::Label(next_lbl).into());
+                    ops.push(BuiltinOp::Label(next_lbl).into_op(pos.clone()));
                 }
             }
-            ops.push(BuiltinOp::Label(end_lbl).into());
+            ops.push(BuiltinOp::Label(end_lbl).into_op(parent_pos));
         }
 
         Ok(ops)
@@ -68,6 +82,17 @@ impl Flatten for InstrWithBranches {
 }
 
 impl Flatten for Vec<Box<dyn Flatten>> {
+    fn pos(&self) -> SourcePosition {
+        match self.first() {
+            None => {
+                Default::default()
+            }
+            Some(f) => {
+                f.pos()
+            }
+        }
+    }
+
     fn flatten(self: Box<Self>, label_num: &AtomicU32) -> Result<Vec<Op>, CrsnError> {
         let mut ops = vec![];
         for item in self.into_iter() {
@@ -78,15 +103,21 @@ impl Flatten for Vec<Box<dyn Flatten>> {
 }
 
 impl Flatten for Routine {
+    fn pos(&self) -> SourcePosition {
+        self.pos.clone()
+    }
+
     fn flatten(self: Box<Self>, label_num: &AtomicU32) -> Result<Vec<Op>, CrsnError> {
         let skip_label = Label::unique(label_num);
 
+        let self_pos = self.pos();
+
         let mut ops: Vec<Op> = vec![
             BuiltinOp::Barrier {
                 kind: Barrier::Open(skip_label.clone()),
                 msg: Some(format!("proc {} start", self.name).into()),
-            }.into(),
+            }.into_op(self.pos()),
-            BuiltinOp::Routine(self.name.clone()).into(),
+            BuiltinOp::Routine(self.name.clone()).into_op(self.pos()),
         ];
 
         ops.extend(self.body.flatten(label_num)?);
@@ -95,7 +126,7 @@ impl Flatten for Routine {
             BuiltinOp::Barrier {
                 kind: Barrier::Close(skip_label.clone()),
                 msg: Some(format!("proc {} end", self.name).into()),
-            }.into()
+            }.into_op(self_pos)
         );
 
         labels_to_skips(ops)
@@ -123,10 +154,11 @@ pub fn labels_to_skips(ops: Vec<Op>) -> Result<Vec<Op>, CrsnError> {
                     let skip = *dest as isize - n as isize + skipped;
                     cleaned.push(Op {
                         cond: op.cond,
+                        pos : op.pos.clone(),
                         kind: OpKind::BuiltIn(BuiltinOp::Skip(Rd::new(RdData::Immediate(skip as Value)))),
                     });
                 } else {
-                    return Err(CrsnError::Asm(AsmError::LabelNotDefined(target)));
+                    return Err(CrsnError::Asm(AsmError::LabelNotDefined(target), op.pos));
                 }
             }
             _ => {

crsn/src/asm/instr/mod.rs

@@ -3,6 +3,7 @@ pub use flatten::Flatten;
 pub use op::Op;
 
 use crate::asm::data::literal::RoutineName;
+use sexp::SourcePosition;
 
 pub mod op;
 pub mod cond;
@@ -12,6 +13,7 @@ pub mod flatten;
 #[derive(Debug)]
 pub struct InstrWithBranches {
     pub op: Op,
+    pub pos: SourcePosition,
     pub branches: Option<Vec<(Cond, Box<dyn Flatten>)>>,
 }
 
@@ -19,5 +21,6 @@ pub struct InstrWithBranches {
 #[derive(Debug)]
 pub struct Routine {
     pub name: RoutineName,
+    pub pos: SourcePosition,
     pub body: Box<dyn Flatten>,
 }

crsn/src/asm/instr/op.rs

@@ -5,7 +5,7 @@ use crate::builtin::defs::BuiltinOp;
 use crate::module::{EvalRes, OpTrait};
 use crate::runtime::fault::Fault;
 use crate::runtime::run_thread::{info::ThreadInfo, state::RunState};
-use sexp::{Sexp, Atom};
+use sexp::{Sexp, Atom, SourcePosition};
 
 /// A higher level simple opration
 #[derive(Debug)]
@@ -18,6 +18,7 @@ pub enum OpKind {
 #[derive(Debug)]
 pub struct Op {
     pub cond: Option<Cond>,
+    pub pos : SourcePosition,
     pub kind: OpKind,
 }
 
@@ -49,8 +50,8 @@ impl OpTrait for Op {
         };
 
         if let Some(cond) = self.cond {
-            if let Sexp::List(items) = &mut se {
+            if let Sexp::List(items, _) = &mut se {
-                if let Some(Sexp::Atom(Atom::S(s))) = &mut items.get_mut(0) {
+                if let Some(Sexp::Atom(Atom::S(s), _)) = &mut items.get_mut(0) {
                     s.push('.');
                     s.push_str(&cond.to_string());
                 }

crsn/src/asm/mod.rs

@@ -5,6 +5,7 @@ use crate::asm::parse::{ParserContext, ParserState};
 use crate::module::CrsnExtension;
 use crate::runtime::program::Program;
 use crate::asm::instr::flatten::labels_to_skips;
+use sexp::SourcePosition;
 
 pub mod data;
 pub mod error;
@@ -23,7 +24,7 @@ pub fn assemble(source: &str, parsers: Arc<Vec<Box<dyn CrsnExtension>>>) -> Resu
         }),
     };
 
-    let ops = parse::parse(source, &pcx)?;
+    let ops = parse::parse(source, SourcePosition::default(), &pcx)?;
     let ops = labels_to_skips(ops)?;
 
     Ok(Program::new(ops, parsers)?)

crsn/src/asm/parse/arg_parser.rs

@@ -1,14 +1,17 @@
-use sexp::Sexp;
+use sexp::{Sexp, SourcePosition};
 
 use crate::asm::data::{Mask, Rd, RdData, RdObj, Wr};
+use crate::asm::error::CrsnError;
 use crate::asm::parse::parse_data::{parse_rd, parse_wr};
 use crate::asm::parse::ParserContext;
 use crate::asm::parse::sexp_expect::expect_string_atom;
+use crate::asm::patches::NextOrErr;
 
 /// Utility for argument parsing
 pub struct TokenParser<'a> {
     orig_len: usize,
     args: Vec<Sexp>,
+    start_pos: SourcePosition,
     pub pcx: &'a ParserContext<'a>,
 }
 
@@ -26,10 +29,11 @@ impl<'a> IntoIterator for TokenParser<'a> {
 
 impl<'a> TokenParser<'a> {
     /// Create a new argument parser
-    pub fn new(mut args: Vec<Sexp>, pcx: &'a ParserContext) -> Self {
+    pub fn new(mut args: Vec<Sexp>, start_pos: SourcePosition, pcx: &'a ParserContext) -> Self {
         args.reverse();
         Self {
             orig_len: args.len(),
+            start_pos,
             args,
             pcx,
         }
@@ -59,37 +63,51 @@ impl<'a> TokenParser<'a> {
         self.args.pop()
     }
 
+    /// Get the next entry, or raise an error
+    pub fn next_or_err(&mut self) -> Result<Sexp, CrsnError> {
+        match self.next() {
+            None => {
+                Err(CrsnError::Parse("Unexpected end of token list".into(), self.start_pos.clone()))
+            }
+            Some(removed) => Ok(removed)
+        }
+    }
+
     /// Look at the next entry
     pub fn peek(&mut self) -> Option<&Sexp> {
         self.args.last()
     }
 
     /// Get the next string entry
-    pub fn next_string(&mut self) -> anyhow::Result<String> {
+    pub fn next_string(&mut self) -> Result<(String, SourcePosition), CrsnError> {
-        let next = self.next();
+        let next = self.next_or_err()?;
         let esa = expect_string_atom(next)?;
         Ok(esa)
     }
 
     /// Get the next entry as read location
-    pub fn next_rd(&mut self) -> anyhow::Result<Rd> {
+    pub fn next_rd(&mut self) -> Result<Rd, CrsnError> {
-        parse_rd(self.next(), self.pcx)
+        let next = self.next_or_err()?;
+        parse_rd(next, self.pcx)
     }
 
     /// Get the next entry as read location
-    pub fn next_rdobj(&mut self) -> anyhow::Result<RdObj> {
+    pub fn next_rdobj(&mut self) -> Result<RdObj, CrsnError> {
-        match parse_rd(self.next(), self.pcx)? {
+        match parse_rd(self.next_or_err()?, self.pcx)? {
             Rd(RdData::ObjectPtr(reg), Mask::FULL) => {
-                return Ok(RdObj::new(reg));
+                Ok(RdObj::new(reg))
             }
             other => {
-                anyhow::bail!("Not a valid object handle syntax: {:?}", other);
+                Err(CrsnError::Parse(
+                    format!("Not a valid object handle syntax: {:?}", other).into(),
+                    self.start_pos.clone(),
+                ))
             }
         }
     }
 
     /// Get the next entry as write location
-    pub fn next_wr(&mut self) -> anyhow::Result<Wr> {
+    pub fn next_wr(&mut self) -> Result<Wr, CrsnError> {
-        parse_wr(self.next(), self.pcx)
+        parse_wr(self.next_or_err()?, self.pcx)
     }
 }

crsn/src/asm/parse/mod.rs

@@ -10,6 +10,7 @@ use crate::asm::error::CrsnError;
 use crate::asm::instr::Op;
 use crate::asm::parse::sexp_expect::expect_list;
 use crate::module::CrsnExtension;
+use sexp::SourcePosition;
 
 pub mod parse_cond;
 pub mod parse_instr;
@@ -38,12 +39,12 @@ pub struct ParserState {
     pub constants: HashMap<ConstantName, Value>,
 }
 
-pub fn parse(source: &str, parsers: &ParserContext) -> Result<Vec<Op>, CrsnError> {
+pub fn parse(source: &str, pos: SourcePosition, parsers: &ParserContext) -> Result<Vec<Op>, CrsnError> {
-    let items = expect_list(Some(sexp::parse(source)?), true)?;
+    let (items, _pos) = expect_list(sexp::parse(source)?, true)?;
 
     /* numbered labels start with a weird high number
     to avoid conflicts with user-defined numbered labels */
     let label_num = AtomicU32::new(0x7890_0000);
-    parse_instructions(items.into_iter(), parsers)?
+    parse_instructions(items.into_iter(), pos, parsers)?
         .flatten(&label_num)
 }

crsn/src/asm/parse/parse_cond.rs

@@ -8,13 +8,13 @@ use crate::asm::parse::sexp_expect::{expect_list, expect_string_atom};
 use crate::asm::patches::TryRemove;
 
 pub fn parse_cond_branch(tok: Sexp, parsers: &ParserContext) -> Result<(Cond, Box<dyn Flatten>), CrsnError> {
-    let mut list = expect_list(Some(tok), false)?;
+    let (mut list, pos) = expect_list(tok, false)?;
-    let kw = expect_string_atom(list.try_remove(0))?;
+    let (kw, kw_pos) = expect_string_atom(list.remove_or_err(0, pos.clone(), "Missing \"cond?\" keyword in conditional branch")?)?;
 
     if !kw.ends_with('?') {
-        return Err(CrsnError::Parse(format!("Condition must end with '?': {}", kw).into()));
+        return Err(CrsnError::Parse(format!("Condition must end with '?': {}", kw).into(), kw_pos));
     }
 
-    Ok((cond::parse_cond(&kw)?, parse_instructions(list.into_iter(), parsers)?))
+    Ok((cond::parse_cond(&kw, kw_pos)?, parse_instructions(list.into_iter(), pos, parsers)?))
 }
 

crsn/src/asm/parse/parse_data.rs

@@ -1,13 +1,15 @@
 use std::borrow::Cow;
 use std::convert::TryFrom;
 
-use sexp::{Atom, Sexp};
+use sexp::{Atom, Sexp, SourcePosition};
 
 use crate::asm::data::{DataDisp, Rd, RdData, reg, Wr, WrData};
 use crate::asm::data::literal::{ConstantName, Label, RegisterAlias, Value};
 use crate::asm::error::CrsnError;
 use crate::asm::parse::ParserContext;
 use crate::asm::parse::sexp_expect::expect_string_atom;
+use std::num::TryFromIntError;
+use crate::asm::patches::ErrWithPos;
 
 fn is_valid_identifier(name: &str) -> bool {
     name.starts_with(|c: char| c.is_ascii_alphabetic() || c == '_')
@@ -15,65 +17,60 @@ fn is_valid_identifier(name: &str) -> bool {
 }
 
 /// Parse register alias
-pub fn parse_reg_alias(name: Option<Sexp>) -> Result<RegisterAlias, CrsnError> {
+pub fn parse_reg_alias(name: Sexp) -> Result<(RegisterAlias, SourcePosition), CrsnError> {
     // trace!("parse reg alias: {:?}", name);
 
-    let name = expect_string_atom(name)?;
+    let (name, namepos) = expect_string_atom(name)?;
 
     if !is_valid_identifier(&name) {
-        return Err(CrsnError::Parse(format!("\"{}\" is not an allowed register alias.", name).into()));
+        return Err(CrsnError::Parse(format!("\"{}\" is not an allowed register alias.", name).into(), namepos));
     }
 
-    Ok(name)
+    Ok((name, namepos))
 }
 
 /// Parse constant name
-pub fn parse_constant_name(name: Option<Sexp>) -> Result<ConstantName, CrsnError> {
+pub fn parse_constant_name(name: Sexp) -> Result<(ConstantName, SourcePosition), CrsnError> {
     // trace!("parse const name: {:?}", name);
 
-    let name = expect_string_atom(name)?;
+    let (name, namepos) = expect_string_atom(name)?;
 
     if !is_valid_identifier(&name) {
-        return Err(CrsnError::Parse(format!("\"{}\" is not an allowed constant name.", name).into()));
+        return Err(CrsnError::Parse(format!("\"{}\" is not an allowed constant name.", name).into(), namepos));
     }
 
-    Ok(name)
+    Ok((name, namepos))
 }
 
 /// Parse a label
-pub fn parse_label(name: Option<Sexp>) -> Result<Label, CrsnError> {
+pub fn parse_label(name: Sexp) -> Result<Label, CrsnError> {
     // trace!("parse label: {:?}", name);
-    let name = expect_string_atom(name)?;
+    let (name, namepos) = expect_string_atom(name)?;
-    Ok(parse_label_str(&name)?)
+    Ok(parse_label_str(&name, namepos)?)
 }
 
-pub fn parse_label_str(name: &str) -> Result<Label, CrsnError> {
+pub fn parse_label_str(name: &str, pos: SourcePosition) -> Result<Label, CrsnError> {
     let label = name.trim_start_matches(':');
 
     Ok(if label.starts_with('#') {
-        Label::Numbered(u32::try_from(parse_u64(&label[1..])?).expect("numbered label fit in u32"))
+        let val = parse_u64(&label[1..], pos.clone())?;
+        Label::Numbered(u32::try_from(val).err_pos(pos)?)
     } else {
         Label::Named(label.to_string())
     })
 }
 
 /// Parse data disposition (address/value, without the read/write restriction)
-pub fn parse_data_disp(tok: Option<Sexp>, pcx: &ParserContext) -> Result<DataDisp, CrsnError> {
+pub fn parse_data_disp(tok: Sexp, pcx: &ParserContext) -> Result<DataDisp, CrsnError> {
     // trace!("parse data: {:?}", tok);
 
-    let tok = if let Some(tok) = tok {
-        tok
-    } else {
-        return Err(CrsnError::Parse("Expected data disposition token".into()));
-    };
-
     // TODO implement masks
 
-    match &tok {
+    match tok {
-        Sexp::Atom(Atom::I(val)) => {
+        Sexp::Atom(Atom::I(val), pos) => {
-            Ok(DataDisp::Immediate(unsafe { std::mem::transmute(*val) }))
+            Ok(DataDisp::Immediate(unsafe { std::mem::transmute(val) }))
         }
-        Sexp::Atom(Atom::S(s)) => {
+        Sexp::Atom(Atom::S(s), pos) => {
             if s == "_" {
                 return Ok(DataDisp::Discard);
             }
@@ -81,11 +78,11 @@ pub fn parse_data_disp(tok: Option<Sexp>, pcx: &ParserContext) -> Result<DataDis
             // check if we have an alias defined
             {
                 let pstate = pcx.state.borrow();
-                if let Some(val) = pstate.constants.get(s) {
+                if let Some(val) = pstate.constants.get(&s) {
                     return Ok(DataDisp::Immediate(*val));
                 }
 
-                if let Some(val) = pstate.reg_aliases.get(s) {
+                if let Some(val) = pstate.reg_aliases.get(&s) {
                     return Ok(DataDisp::Register(*val));
                 }
             }
@@ -95,63 +92,55 @@ pub fn parse_data_disp(tok: Option<Sexp>, pcx: &ParserContext) -> Result<DataDis
                 if let Some(val) = pstate.reg_aliases.get(reference) {
                     Ok(DataDisp::ObjectPtr(*val))
                 } else {
-                    let reg = reg::parse_reg(reference)?;
+                    let reg = reg::parse_reg(reference, pos.clone())?;
 
                     if pstate.reg_aliases.values().find(|v| **v == reg).is_some() {
-                        Err(CrsnError::Parse(format!("Sym exists for register {}, direct access denied. Unsym it if needed.", reg).into()))
+                        Err(CrsnError::Parse(format!("Sym exists for register {}, direct access denied. Unsym it if needed.", reg).into(), pos))
                     } else {
                         Ok(DataDisp::ObjectPtr(reg))
                     }
                 }
             } else if s.starts_with(|c: char| c.is_ascii_digit()) {
-                Ok(DataDisp::Immediate(unsafe { std::mem::transmute(parse_i64(s)?) }))
+                Ok(DataDisp::Immediate(unsafe { std::mem::transmute(parse_i64(&s, pos)?) }))
             } else {
-                let reg = reg::parse_reg(s)?;
+                let reg = reg::parse_reg(&s, pos.clone())?;
 
                 let pstate = pcx.state.borrow();
                 if pstate.reg_aliases.values().find(|v| **v == reg).is_some() {
-                    Err(CrsnError::Parse(format!("Sym exists for register {}, direct access denied. Unsym it if needed.", reg).into()))
+                    Err(CrsnError::Parse(format!("Sym exists for register {}, direct access denied. Unsym it if needed.", reg).into(), pos))
                 } else {
                     Ok(DataDisp::Register(reg))
                 }
             }
         }
-        _ => {
+        other => {
-            Err(CrsnError::Parse(format!("bad data disp: {:?}", tok).into()))
+            Err(CrsnError::Parse(format!("bad data disp: {:?}", other).into(), other.pos().clone()))
         }
     }
 }
 
 /// Parse immediate value
-pub fn parse_value(tok: Option<Sexp>, pcx: &ParserContext) -> Result<Value, CrsnError> {
+pub fn parse_value(tok: Sexp, pcx: &ParserContext) -> Result<Value, CrsnError> {
-    let tok = if let Some(tok) = tok {
+    match tok {
-        tok
+        Sexp::Atom(Atom::I(val), pos) => {
-    } else {
+            Ok(unsafe { std::mem::transmute(val) })
-        return Err(CrsnError::Parse("Expected value token".into()));
-    };
-
-    // trace!("parse value: {:?}", tok);
-
-    match &tok {
-        Sexp::Atom(Atom::I(val)) => {
-            Ok(unsafe { std::mem::transmute(*val) })
         }
-        Sexp::Atom(Atom::S(s)) => {
+        Sexp::Atom(Atom::S(s), pos) => {
             let pstate = pcx.state.borrow();
-            if let Some(val) = pstate.constants.get(s) {
+            if let Some(val) = pstate.constants.get(&s) {
                 return Ok(*val);
             }
 
-            Ok(unsafe { std::mem::transmute(parse_i64(s)?) })
+            Ok(unsafe { std::mem::transmute(parse_i64(&s, pos)?) })
         }
-        _ => {
+        other => {
-            Err(CrsnError::Parse(format!("bad value format: {:?}", tok).into()))
+            Err(CrsnError::Parse(format!("bad value format: {:?}", other).into(), other.pos().clone()))
         }
     }
 }
 
 
-pub fn parse_u64(literal: &str) -> anyhow::Result<u64> {
+pub fn parse_u64(literal: &str, pos: SourcePosition) -> Result<u64, CrsnError> {
     // trace!("parse u64 from {}", literal);
     let mut without_underscores = Cow::Borrowed(literal);
     if without_underscores.contains('_') {
@@ -159,27 +148,29 @@ pub fn parse_u64(literal: &str) -> anyhow::Result<u64> {
     }
 
     if let Some(hex) = without_underscores.strip_prefix("0x") {
-        Ok(u64::from_str_radix(hex, 16)?)
+        Ok(u64::from_str_radix(hex, 16).err_pos(pos)?)
     } else if let Some(hex) = without_underscores.strip_prefix("0b") {
-        Ok(u64::from_str_radix(hex, 2)?)
+        Ok(u64::from_str_radix(hex, 2).err_pos(pos)?)
     } else {
-        Ok(u64::from_str_radix(&without_underscores, 10)?)
+        Ok(u64::from_str_radix(&without_underscores, 10).err_pos(pos)?)
     }
 }
 
-pub fn parse_i64(literal: &str) -> anyhow::Result<i64> {
+pub fn parse_i64(literal: &str, pos: SourcePosition) -> Result<i64, CrsnError> {
     // trace!("parse i64 from {}", literal);
     if let Some(_value) = literal.strip_prefix("-") {
-        Ok(-1 * i64::try_from(parse_u64(literal)?)?)
+        Ok(-1 * i64::try_from(parse_u64(literal, pos.clone())?).err_pos(pos)?)
     } else {
-        Ok(i64::try_from(parse_u64(literal)?)?)
+        Ok(i64::try_from(parse_u64(literal, pos.clone())?).err_pos(pos)?)
     }
 }
 
-pub fn parse_rd(tok: Option<Sexp>, pcx: &ParserContext) -> anyhow::Result<Rd> {
+pub fn parse_rd(tok: Sexp, pcx: &ParserContext) -> Result<Rd, CrsnError> {
-    Ok(Rd::new(RdData::try_from(parse_data_disp(tok, pcx)?)?))
+    let pos = tok.pos().clone();
+    Ok(Rd::new(RdData::try_from(parse_data_disp(tok, pcx)?).err_pos(pos)?))
 }
 
-pub fn parse_wr(tok: Option<Sexp>, pcx: &ParserContext) -> anyhow::Result<Wr> {
+pub fn parse_wr(tok: Sexp, pcx: &ParserContext) -> Result<Wr, CrsnError> {
-    Ok(Wr::new(WrData::try_from(parse_data_disp(tok, pcx)?)?))
+    let pos = tok.pos().clone();
+    Ok(Wr::new(WrData::try_from(parse_data_disp(tok, pcx)?).err_pos(pos)?))
 }

crsn/src/asm/parse/parse_instr.rs

@@ -1,4 +1,4 @@
-use sexp::Sexp;
+use sexp::{Sexp, SourcePosition};
 
 use crate::asm::error::CrsnError;
 use crate::asm::instr::{Flatten, InstrWithBranches};
@@ -7,27 +7,27 @@ use crate::asm::parse::parse_cond::parse_cond_branch;
 use crate::asm::parse::parse_routine::parse_routine;
 use crate::asm::parse::ParserContext;
 use crate::asm::parse::sexp_expect::{expect_list, expect_string_atom};
-use crate::asm::patches::SexpIsA;
 use crate::module::ParseRes;
 
 use super::parse_op::parse_op;
+use crate::asm::patches::NextOrErr;
 
-pub fn parse_instructions(items: impl Iterator<Item=Sexp>, pcx: &ParserContext) -> Result<Box<dyn Flatten>, CrsnError> {
+pub fn parse_instructions(items: impl Iterator<Item=Sexp>, pos: SourcePosition, pcx: &ParserContext) -> Result<Box<dyn Flatten>, CrsnError> {
     let mut parsed = vec![];
     for expr in items {
-        let tokens = expect_list(Some(expr), false)?;
+        let (tokens, listpos) = expect_list(expr, false)?;
 
         let mut toki = tokens.into_iter();
-        let name = expect_string_atom(toki.next())?;
+        let (name, namepos) = expect_string_atom(toki.next_or_err(listpos.clone(), "Expected instruction name token")?)?;
 
         if name == "proc" {
-            parsed.push(parse_routine(toki, pcx)?);
+            parsed.push(parse_routine(toki, pos.clone(), pcx)?);
             continue;
         }
 
-        let mut token_parser = TokenParser::new(toki.collect(), pcx);
+        let mut token_parser = TokenParser::new(toki.collect(), listpos.clone(), pcx);
         for p in pcx.parsers {
-            token_parser = match p.parse_syntax(&name, token_parser) {
+            token_parser = match p.parse_syntax(pos.clone(), &name, token_parser) {
                 Ok(ParseRes::Parsed(op)) => return Ok(op),
                 Ok(ParseRes::ParsedNone) => return Ok(Box::new(())),
                 Ok(ParseRes::Unknown(to_reuse)) => {
@@ -45,7 +45,7 @@ pub fn parse_instructions(items: impl Iterator<Item=Sexp>, pcx: &ParserContext)
         // Get back the original iterator
         let toki = token_parser.into_iter();
 
-        let arg_tokens = TokenParser::new(toki.clone().take_while(|e| e.is_atom()).collect(), pcx);
+        let arg_tokens = TokenParser::new(toki.clone().take_while(|e| e.is_atom()).collect(), listpos.clone(), pcx);
         let branch_tokens = toki
             .skip_while(|e| e.is_atom())
             .take_while(|e| e.is_list());
@@ -62,9 +62,10 @@ pub fn parse_instructions(items: impl Iterator<Item=Sexp>, pcx: &ParserContext)
             }
         };
 
-        if let Some(op) = parse_op(name.as_str(), arg_tokens)? {
+        if let Some(op) = parse_op(name.as_str(), arg_tokens, namepos.clone())? {
             parsed.push(Box::new(InstrWithBranches {
                 op,
+                pos: namepos,
                 branches,
             }));
         }

crsn/src/asm/parse/parse_op.rs

@@ -4,27 +4,29 @@ use crate::asm::instr::Op;
 use crate::asm::parse::arg_parser::TokenParser;
 use crate::module::ParseRes;
 use crate::builtin::BuiltinOps;
+use sexp::SourcePosition;
 
-pub fn parse_op<'a>(mut keyword: &str, mut arg_tokens: TokenParser<'a>) -> Result<Option<Op>, CrsnError> {
+pub fn parse_op<'a>(mut keyword: &str, mut arg_tokens: TokenParser<'a>, spos: SourcePosition) -> Result<Option<Op>, CrsnError> {
     // Include built-in instructions
     let builtins = [BuiltinOps::new()];
     let mut cond = None;
 
     if let Some(pos) = keyword.find('.') {
-        cond = Some(parse_cond(&keyword[(pos + 1)..])?);
+        cond = Some(parse_cond(&keyword[(pos + 1)..], spos.clone())?);
         keyword = &keyword[..pos];
     }
 
     for p in builtins.iter().chain(arg_tokens.pcx.parsers) {
-        arg_tokens = match p.parse_op(keyword, arg_tokens) {
+        arg_tokens = match p.parse_op(spos.clone(), keyword, arg_tokens) {
             Ok(ParseRes::Parsed(kind)) => return Ok(Some(Op {
                 cond,
+                pos: spos,
                 kind,
             })),
             Ok(ParseRes::ParsedNone) => return Ok(None),
             Ok(ParseRes::Unknown(to_reuse)) => {
                 if to_reuse.parsing_started() {
-                    panic!("Module \"{}\" started parsing {}, but returned Unknown!", p.name(), keyword);
+                    return Err(CrsnError::Parse(format!("Module \"{}\" started parsing {}, but returned Unknown!", p.name(), keyword).into(), spos));
                 }
                 to_reuse
             }
@@ -34,5 +36,5 @@ pub fn parse_op<'a>(mut keyword: &str, mut arg_tokens: TokenParser<'a>) -> Resul
         }
     }
 
-    return Err(CrsnError::Parse(format!("Unknown instruction: {}", keyword).into()));
+    return Err(CrsnError::Parse(format!("Unknown instruction: {}", keyword).into(), spos));
 }

crsn/src/asm/parse/parse_routine.rs

@@ -1,4 +1,4 @@
-use sexp::Sexp;
+use sexp::{Sexp, SourcePosition};
 
 use crate::asm::data::Register;
 use crate::asm::error::CrsnError;
@@ -7,14 +7,14 @@ use crate::asm::parse::{parse_instructions, ParserContext};
 use crate::asm::parse::arg_parser::TokenParser;
 use crate::asm::parse::parse_data::parse_reg_alias;
 use crate::asm::parse::sexp_expect::expect_string_atom;
-use crate::asm::patches::SexpIsA;
 use crate::builtin::parse::parse_routine_name;
+use crate::asm::patches::NextOrErr;
 
-pub fn parse_routine(mut toki: impl Iterator<Item=Sexp> + Clone, pcx: &ParserContext) -> Result<Box<dyn Flatten>, CrsnError> {
+pub fn parse_routine(mut toki: impl Iterator<Item=Sexp> + Clone, rt_pos: SourcePosition, pcx: &ParserContext) -> Result<Box<dyn Flatten>, CrsnError> {
-    let name = expect_string_atom(toki.next())?;
+    let (name, namepos) = expect_string_atom(toki.next_or_err(rt_pos.clone(), "Expected routine name")?)?;
-    let mut name = parse_routine_name(name)?;
+    let mut name = parse_routine_name(name, namepos)?;
 
-    let arg_tokens = TokenParser::new(toki.clone().take_while(|e| e.is_atom()).collect(), pcx);
+    let arg_tokens = TokenParser::new(toki.clone().take_while(|e| e.is_atom()).collect(), rt_pos.clone(), pcx);
 
     // If arity is explicitly given, then either no named argument must be provided,
     // or their count must match the arity. If no arity is given, then arity is determined
@@ -22,7 +22,7 @@ pub fn parse_routine(mut toki: impl Iterator<Item=Sexp> + Clone, pcx: &ParserCon
     if name.arity == 0 && arg_tokens.len() != 0 {
         name.arity = arg_tokens.len() as u8;
     } else if arg_tokens.len() != 0 && name.arity as usize != arg_tokens.len() {
-        return Err(CrsnError::Parse(format!("arity mismatch in routine {}", name.name).into()));
+        return Err(CrsnError::Parse(format!("arity mismatch in routine {}", name.name).into(), rt_pos));
     }
 
     let toki = toki.skip_while(|e| e.is_atom());
@@ -34,17 +34,17 @@ pub fn parse_routine(mut toki: impl Iterator<Item=Sexp> + Clone, pcx: &ParserCon
         pstate.reg_alias_stack.push(old);
 
         for (n, tok) in arg_tokens.into_iter().enumerate() {
-            let alias = parse_reg_alias(Some(tok))?;
+            let alias = parse_reg_alias(tok)?;
 
-            if pstate.constants.contains_key(&alias) {
+            if pstate.constants.contains_key(&alias.0) {
-                return Err(CrsnError::Parse(format!("Symbol \"{}\" already used for a constant.", alias).into()));
+                return Err(CrsnError::Parse(format!("Symbol \"{}\" already used for a constant.", alias.0).into(), alias.1));
             }
 
-            pstate.reg_aliases.insert(alias, Register::Arg(n as u8));
+            pstate.reg_aliases.insert(alias.0, Register::Arg(n as u8));
         }
     }
 
-    let body = parse_instructions(toki, pcx)?;
+    let body = parse_instructions(toki, rt_pos.clone(), pcx)?;
 
     {
         let mut pstate = pcx.state.borrow_mut();
@@ -54,6 +54,7 @@ pub fn parse_routine(mut toki: impl Iterator<Item=Sexp> + Clone, pcx: &ParserCon
 
     return Ok(Box::new(Routine {
         name,
+        pos: rt_pos,
         body,
     }));
 }

crsn/src/asm/parse/sexp_expect.rs

@@ -1,53 +1,37 @@
-use sexp::{Atom, Sexp};
+use sexp::{Atom, Sexp, SourcePosition};
 
 use crate::asm::error::CrsnError;
 
-pub fn expect_list(expr: Option<Sexp>, allow_empty: bool) -> Result<Vec<Sexp>, CrsnError> {
+pub fn expect_list(expr: Sexp, allow_empty: bool) -> Result<(Vec<Sexp>, SourcePosition), CrsnError> {
-    if let Some(expr) = expr {
+    match expr {
-        match &expr {
+        Sexp::Atom(_, pos) => {
-            Sexp::Atom(_) => {
+            return Err(CrsnError::Parse("Expected a list".into(), pos));
-                return Err(CrsnError::ParseIn("Expected a list".into(), expr));
+        }
+        Sexp::List(list, pos) => {
+            if !allow_empty && list.is_empty() {
+                return Err(CrsnError::Parse("Routine: Empty list".into(), pos));
             }
-            Sexp::List(list) => {
-                if !allow_empty && list.is_empty() {
-                    return Err(CrsnError::ParseIn("Routine: Empty list".into(), expr));
-                }
 
-                if let Sexp::List(list) = expr {
+            Ok((list, pos))
-                    return Ok(list);
-                } else {
-                    unreachable!();
-                }
-            }
         }
     }
-
-    Err(CrsnError::Parse("Expected a list, got nothing".into()))
 }
 
-pub fn expect_atom(expr: Option<Sexp>) -> Result<Atom, CrsnError> {
+pub fn expect_atom(expr: Sexp) -> Result<(Atom, SourcePosition), CrsnError> {
-    if let Some(expr) = expr {
+    match expr {
-        match &expr {
+        Sexp::Atom(a, pos) => {
-            Sexp::Atom(_atom) => {
+            Ok((a, pos))
-                if let Sexp::Atom(a) = expr {
+        }
-                    return Ok(a);
+        Sexp::List(_, pos) => {
-                } else {
+            return Err(CrsnError::Parse("Expected atom got list".into(), pos));
-                    unreachable!();
-                }
-            }
-            Sexp::List(_) => {
-                return Err(CrsnError::ParseIn("Expected atom got list".into(), expr));
-            }
         }
     }
-
-    Err(CrsnError::Parse("Expected atom, got nothing".into()))
 }
 
-pub fn expect_string_atom(expr: Option<Sexp>) -> Result<String, CrsnError> {
+pub fn expect_string_atom(expr: Sexp) -> Result<(String, SourcePosition), CrsnError> {
     match expect_atom(expr) {
-        Ok(Atom::S(s)) => Ok(s),
+        Ok((Atom::S(s), pos)) => Ok((s, pos)),
-        Ok(atom) => Err(CrsnError::ParseIn("Expected string atom".into(), Sexp::Atom(atom))),
+        Ok((_, pos)) => Err(CrsnError::Parse("Expected string atom".into(), pos)),
         Err(e) => Err(e),
     }
 }

crsn/src/asm/patches/mod.rs

@@ -1,6 +1,59 @@
-pub use sexp_is_a::SexpIsA;
+use sexp::SourcePosition;
-pub use try_remove::TryRemove;
+use crate::asm::error::CrsnError;
+use std::borrow::Cow;
 
-mod try_remove;
+pub trait TryRemove {
-mod sexp_is_a;
+    type Item;
+    fn try_remove(&mut self, index: usize) -> Option<Self::Item>;
 
+    fn remove_or_err(&mut self, index: usize, pos: SourcePosition, err : &'static str) -> Result<Self::Item, CrsnError>;
+}
+
+impl<T> TryRemove for Vec<T> {
+    type Item = T;
+
+    fn try_remove(&mut self, index: usize) -> Option<T> {
+        if self.is_empty() {
+            None
+        } else {
+            Some(self.remove(index))
+        }
+    }
+
+    fn remove_or_err(&mut self, index: usize, pos: SourcePosition, err : &'static str) -> Result<Self::Item, CrsnError> {
+        match self.try_remove(index) {
+            None => {
+                Err(CrsnError::Parse(err.into(), pos))
+            }
+            Some(removed) => Ok(removed)
+        }
+    }
+}
+
+pub trait NextOrErr<T> {
+    fn next_or_err(&mut self, pos: SourcePosition, err : &'static str) -> Result<T, CrsnError>;
+}
+
+impl<T, K : Iterator<Item=T>> NextOrErr<T> for K {
+    fn next_or_err(&mut self, pos: SourcePosition, err: &'static str) -> Result<T, CrsnError> {
+        match self.next() {
+            None => {
+                Err(CrsnError::Parse(err.into(), pos))
+            }
+            Some(removed) => Ok(removed)
+        }
+    }
+}
+
+pub trait ErrWithPos<T> {
+    fn err_pos(self, pos : SourcePosition) -> Result<T, CrsnError>;
+}
+
+impl<T, E : std::error::Error + Send + Sync + 'static> ErrWithPos<T> for Result<T, E> {
+    fn err_pos(self, pos : SourcePosition) -> Result<T, CrsnError> {
+        match self {
+            Ok(v) => Ok(v),
+            Err(e) => Err(CrsnError::ParseOther(Box::new(e), pos))
+        }
+    }
+}

crsn/src/asm/patches/sexp_is_a.rs

@@ -1,23 +0,0 @@
-use sexp::Sexp;
-
-pub trait SexpIsA {
-    fn is_atom(&self) -> bool;
-
-    fn is_list(&self) -> bool;
-}
-
-impl SexpIsA for Sexp {
-    fn is_atom(&self) -> bool {
-        match self {
-            Sexp::Atom(_) => true,
-            _ => false,
-        }
-    }
-
-    fn is_list(&self) -> bool {
-        match self {
-            Sexp::List(_) => true,
-            _ => false,
-        }
-    }
-}

crsn/src/asm/patches/try_remove.rs

@@ -1,17 +0,0 @@
-pub trait TryRemove {
-    type Item;
-    fn try_remove(&mut self, index: usize) -> Option<Self::Item>;
-}
-
-impl<T> TryRemove for Vec<T> {
-    type Item = T;
-
-    fn try_remove(&mut self, index: usize) -> Option<T> {
-        if self.is_empty() {
-            None
-        } else {
-            Some(self.remove(index))
-        }
-    }
-}
-

crsn/src/builtin/defs.rs

@@ -2,6 +2,7 @@ use crate::asm::data::{Rd, RdObj, Wr};
 use crate::asm::data::literal::{DebugMsg, Label, RoutineName};
 use crate::asm::instr::Op;
 use crate::asm::instr::op::OpKind;
+use sexp::SourcePosition;
 
 #[derive(Debug)]
 pub enum Barrier {
@@ -60,10 +61,11 @@ pub enum BuiltinOp {
     LoadStatus { src: Rd },
 }
 
-impl From<BuiltinOp> for Op {
+impl BuiltinOp {
-    fn from(bo: BuiltinOp) -> Self {
+    pub fn into_op(self: BuiltinOp, pos: SourcePosition) -> Op {
         Op {
-            kind: bo.into(),
+            kind: self.into(),
+            pos,
             cond: None,
         }
     }

crsn/src/builtin/mod.rs

@@ -2,6 +2,7 @@ use crate::module::{CrsnExtension, ParseRes};
 use crate::asm::parse::arg_parser::TokenParser;
 use crate::asm::instr::op::OpKind;
 use crate::asm::error::CrsnError;
+use sexp::SourcePosition;
 
 pub mod defs;
 pub mod exec;
@@ -21,7 +22,7 @@ impl CrsnExtension for BuiltinOps {
         "builtin"
     }
 
-    fn parse_op<'a>(&self, keyword: &str, args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
+    fn parse_op<'a>(&self, pos: SourcePosition, keyword: &str, args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
-        parse::parse_op(keyword, args)
+        parse::parse_op(pos, keyword, args)
     }
 }

crsn/src/builtin/parse.rs

@@ -1,4 +1,4 @@
-use sexp::{Atom, Sexp};
+use sexp::{Atom, Sexp, SourcePosition};
 
 use crate::asm::data::literal::{Label, RoutineName};
 use crate::asm::data::reg::parse_reg;
@@ -10,9 +10,10 @@ use crate::asm::parse::sexp_expect::expect_string_atom;
 use crate::builtin::defs::{Barrier, BuiltinOp};
 use crate::module::{ParseRes};
 use crate::utils::A;
+use crate::asm::patches::ErrWithPos;
 
 
-pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
+pub(crate) fn parse_op<'a>(op_pos: SourcePosition, keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
     let pcx = args.pcx;
 
     Ok(ParseRes::Parsed(OpKind::BuiltIn(match keyword {
@@ -31,22 +32,23 @@ pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<P
         }
 
         "sym" => {
-            let alias = parse_reg_alias(args.next())?;
+            let (alias, aliaspos) = parse_reg_alias(args.next_or_err()?)?;
             trace!("alias={:?}", alias);
-            let register = parse_reg(&args.next_string()?)?;
+            let (rn, rpos) = args.next_string()?;
+            let register = parse_reg(&rn, rpos.clone())?;
             trace!("register={:?}", alias);
 
             let mut pstate = pcx.state.borrow_mut();
             if pstate.reg_aliases.contains_key(&alias) {
-                return Err(CrsnError::Parse(format!("Register alias \"{}\" already defined!", alias).into()));
+                return Err(CrsnError::Parse(format!("Register alias \"{}\" already defined!", alias).into(), rpos));
             }
 
             if pstate.constants.contains_key(&alias) {
-                return Err(CrsnError::Parse(format!("Name \"{}\" already used for a constant!", alias).into()));
+                return Err(CrsnError::Parse(format!("Name \"{}\" already used for a constant!", alias).into(), aliaspos));
             }
 
             if pstate.reg_aliases.iter().find(|x| x.1 == &register).is_some() {
-                return Err(CrsnError::Parse(format!("Register \"{}\" already aliased!", register).into()));
+                return Err(CrsnError::Parse(format!("Register \"{}\" already aliased!", register).into(), rpos));
             }
 
             pstate.reg_aliases.insert(alias, register);
@@ -55,26 +57,26 @@ pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<P
         }
 
         "unsym" => {
-            let alias = parse_reg_alias(args.next())?;
+            let alias = parse_reg_alias(args.next_or_err()?)?;
 
             let mut pstate = pcx.state.borrow_mut();
-            if pstate.reg_aliases.remove(&alias).is_none() {
+            if pstate.reg_aliases.remove(&alias.0).is_none() {
-                return Err(CrsnError::Parse(format!("Register alias \"{}\" not defined!", alias).into()));
+                return Err(CrsnError::Parse(format!("Register alias \"{}\" not defined!", alias.0).into(), alias.1));
             }
             return Ok(ParseRes::ParsedNone);
         }
 
         "def" => {
-            let name = parse_constant_name(args.next())?;
+            let (name, namepos) = parse_constant_name(args.next_or_err()?)?;
-            let value = parse_value(args.next(), pcx)?;
+            let value = parse_value(args.next_or_err()?, pcx)?;
 
             let mut pstate = pcx.state.borrow_mut();
             if pstate.constants.contains_key(&name) {
-                return Err(CrsnError::Parse(format!("Constant \"{}\" already defined!", name).into()));
+                return Err(CrsnError::Parse(format!("Constant \"{}\" already defined!", name).into(), namepos));
             }
 
             if pstate.reg_aliases.contains_key(&name) {
-                return Err(CrsnError::Parse(format!("Name \"{}\" already used for a register alias!", name).into()));
+                return Err(CrsnError::Parse(format!("Name \"{}\" already used for a register alias!", name).into(), namepos));
             }
 
             pstate.constants.insert(name, value);
@@ -83,31 +85,31 @@ pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<P
         }
 
         "undef" => {
-            let name = parse_constant_name(args.next())?;
+            let (name, namepos) = parse_constant_name(args.next_or_err()?)?;
 
             let mut pstate = pcx.state.borrow_mut();
             if pstate.constants.remove(&name).is_none() {
-                return Err(CrsnError::Parse(format!("Constant \"{}\" not defined!", name).into()));
+                return Err(CrsnError::Parse(format!("Constant \"{}\" not defined!", name).into(), namepos));
             }
             return Ok(ParseRes::ParsedNone);
         }
 
         "j" => {
-            let dest = parse_label(args.next())?;
+            let dest = parse_label(args.next_or_err()?)?;
             BuiltinOp::Jump(dest)
         }
 
         "fj" => {
-            let dest = parse_label(args.next())?;
+            let dest = parse_label(args.next_or_err()?)?;
             BuiltinOp::FarJump(dest)
         }
 
         "call" => {
-            let dest = RoutineName { name: args.next_string()?, arity: args.len() as u8 };
+            let dest = RoutineName { name: args.next_string()?.0, arity: args.len() as u8 };
 
             let mut call_args = vec![];
             for t in args {
-                call_args.push(parse_rd(Some(t), pcx)?);
+                call_args.push(parse_rd(t, pcx)?);
             }
             BuiltinOp::Call(dest, call_args)
         }
@@ -115,14 +117,14 @@ pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<P
         "ret" => {
             let mut ret_vals = vec![];
             for t in args {
-                ret_vals.push(parse_rd(Some(t), pcx)?);
+                ret_vals.push(parse_rd(t, pcx)?);
             }
             BuiltinOp::Ret(ret_vals)
         }
 
         "routine" => {
             let name = args.next_string()?;
-            BuiltinOp::Routine(parse_routine_name(name)?)
+            BuiltinOp::Routine(parse_routine_name(name.0, name.1)?)
         }
 
         "skip" => {
@@ -134,21 +136,21 @@ pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<P
                 kind: Barrier::Standalone,
                 msg: match args.next() {
                     None => None,
-                    Some(s) => Some(expect_string_atom(Some(s))?.into()),
+                    Some(s) => Some(expect_string_atom(s)?.0.into()),
                 },
             }
         }
 
         "barrier-open" => {
             BuiltinOp::Barrier {
-                kind: Barrier::Open(parse_label(args.next())?),
+                kind: Barrier::Open(parse_label(args.next_or_err()?)?),
                 msg: None,
             }
         }
 
         "barrier-close" => {
             BuiltinOp::Barrier {
-                kind: Barrier::Close(parse_label(args.next())?),
+                kind: Barrier::Close(parse_label(args.next_or_err()?)?),
                 msg: None,
             }
         }
@@ -156,7 +158,7 @@ pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<P
         "fault" => {
             BuiltinOp::Fault(match args.next() {
                 None => None,
-                Some(s) => Some(expect_string_atom(Some(s))?.into()),
+                Some(s) => Some(expect_string_atom(s)?.0.into()),
             })
         }
 
@@ -184,7 +186,7 @@ pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<P
         }
 
         "far" => {
-            if let Some(Sexp::Atom(Atom::S(ref label))) = args.peek() {
+            if let Some(Sexp::Atom(Atom::S(ref label), _)) = args.peek() {
                 if let Some(label) = label.strip_prefix(':') {
                     let label = Label::Named(label.to_string());
                     BuiltinOp::FarLabel(label)
@@ -198,7 +200,7 @@ pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<P
 
         other => {
             if let Some(label) = other.strip_prefix(':') {
-                BuiltinOp::Label(parse_label_str(label)?)
+                BuiltinOp::Label(parse_label_str(label, op_pos)?)
             } else {
                 return Ok(ParseRes::Unknown(args));
             }
@@ -206,11 +208,11 @@ pub(crate) fn parse_op<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<P
     })))
 }
 
-pub(crate) fn parse_routine_name(name: String) -> Result<RoutineName, CrsnError> {
+pub(crate) fn parse_routine_name(name: String, pos: SourcePosition) -> Result<RoutineName, CrsnError> {
     let (name, arity) = if let Some(n) = name.find('/') {
         (
             (&name[0..n]).to_string(),
-            (&name[(n + 1)..]).parse::<u8>()?
+            (&name[(n + 1)..]).parse::<u8>().err_pos(pos)?
         )
     } else {
         (name, 0)

crsn/src/module/mod.rs

@@ -13,7 +13,7 @@ use crate::asm::parse::arg_parser::TokenParser;
 use crate::runtime::fault::Fault;
 use crate::runtime::run_thread::state::RunState;
 use crate::runtime::run_thread::ThreadInfo;
-use sexp::Sexp;
+use sexp::{Sexp, SourcePosition};
 
 
 mod eval_res;
@@ -53,12 +53,12 @@ pub trait CrsnExtension: Debug + Send + Sync + 'static {
     /// If the instruction keyword is not recognized, return Unknown with the unchanged argument list.
     ///
     /// pcx is available on the arg_tokens parser
-    fn parse_op<'a>(&self, keyword: &str, arg_tokens: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError>;
+    fn parse_op<'a>(&self, pos: SourcePosition, keyword: &str, arg_tokens: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError>;
 
     /// Parse a generic S-expression (non-op)
     ///
     /// pcx is available on the arg_tokens parser
-    fn parse_syntax<'a>(&self, keyword: &str, tokens: TokenParser<'a>)
+    fn parse_syntax<'a>(&self, pos: SourcePosition, keyword: &str, tokens: TokenParser<'a>)
                         -> Result<ParseRes<'a, Box<dyn Flatten>>, CrsnError>
     {
         Ok(ParseRes::Unknown(tokens))

crsn/src/runtime/program.rs

@@ -7,6 +7,8 @@ use crate::asm::instr::op::OpKind;
 use crate::builtin::defs::{Barrier, BuiltinOp};
 use crate::module::CrsnExtension;
 use crate::runtime::fault::Fault;
+use sexp::SourcePosition;
+use crate::asm::error::CrsnError;
 
 #[derive(Debug)]
 pub struct Program {
@@ -20,7 +22,7 @@ pub struct Program {
 }
 
 impl Program {
-    pub fn new(ops: Vec<Op>, extensions: Arc<Vec<Box<dyn CrsnExtension>>>) -> anyhow::Result<Arc<Self>> {
+    pub fn new(ops: Vec<Op>, extensions: Arc<Vec<Box<dyn CrsnExtension>>>) -> Result<Arc<Self>, CrsnError> {
         let mut p = Self {
             ops,
             extensions,
@@ -33,7 +35,7 @@ impl Program {
     }
 
     /// Find all the named things
-    fn scan(&mut self) -> anyhow::Result<()> {
+    fn scan(&mut self) -> Result<(), CrsnError> {
         let mut barrier_starts: HashMap<&Label, Addr> = HashMap::new();
         for (pos, op) in self.ops.iter().enumerate() {
             match &op.kind {
@@ -60,7 +62,7 @@ impl Program {
                         self.barriers.push((start_pos, pos.into()));
                         self.far_labels.insert(lbl.clone(), pos.into());
                     } else {
-                        anyhow::bail!("Block barrier \"{:?}\" closed without being open!", msg);
+                        return Err(CrsnError::Parse(format!("Block barrier \"{:?}\" closed without being open!", msg).into(), op.pos.clone()));
                     }
                 }
                 OpKind::BuiltIn(
@@ -76,7 +78,9 @@ impl Program {
         }
 
         if !barrier_starts.is_empty() {
-            anyhow::bail!("Some block barriers open without being closed!");
+            return Err(CrsnError::Parse(format!("Block barrier open without being closed: {}",
+                                                barrier_starts.iter().next().unwrap().0).into(),
+                                        Default::default()));
         }
 
         trace!("Program scanned: {:?}", self);
@@ -87,7 +91,15 @@ impl Program {
     /// Read a program instruction at address
     pub fn read(&self, addr: Addr) -> &Op {
         if addr.0 >= self.ops.len() as u64 {
-            &Op { kind: OpKind::BuiltIn(BuiltinOp::Halt), cond: None }
+            &Op {
+                kind: OpKind::BuiltIn(BuiltinOp::Halt),
+                pos: SourcePosition {
+                    line: 0,
+                    column: 0,
+                    index: 0
+                },
+                cond: None
+            }
         } else {
             &self.ops[addr.0 as usize]
         }

crsn/src/utils/mod.rs

@@ -12,13 +12,13 @@ pub fn A(s: impl Display) -> Sexp {
 
     let x: Result<i64, _> = FromStr::from_str(&s);
     if let Ok(x) = x {
-        return Sexp::Atom(Atom::I(x));
+        return Sexp::Atom(Atom::I(x), Default::default());
     }
 
     let y: Result<f64, _> = FromStr::from_str(&s);
     if let Ok(y) = y {
-        return Sexp::Atom(Atom::F(y));
+        return Sexp::Atom(Atom::F(y), Default::default());
     }
 
-    Sexp::Atom(Atom::S(s))
+    Sexp::Atom(Atom::S(s), Default::default())
 }

crsn_arith/src/lib.rs

@@ -2,6 +2,7 @@ use crsn::asm::error::CrsnError;
 use crsn::asm::instr::op::OpKind;
 use crsn::asm::parse::arg_parser::TokenParser;
 use crsn::module::{CrsnExtension, ParseRes};
+use crsn::sexp::SourcePosition;
 
 mod defs;
 mod parse;
@@ -21,7 +22,7 @@ impl CrsnExtension for ArithOps {
         "arith"
     }
 
-    fn parse_op<'a>(&self, keyword: &str, args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
+    fn parse_op<'a>(&self, pos: SourcePosition, keyword: &str, args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
-        parse::parse(keyword, args)
+        parse::parse(pos, keyword, args)
     }
 }

crsn_arith/src/parse.rs

@@ -5,8 +5,9 @@ use crsn::asm::parse::arg_parser::TokenParser;
 use crsn::module::ParseRes;
 
 use crate::defs::ArithOp;
+use crsn::sexp::SourcePosition;
 
-pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
+pub(crate) fn parse<'a>(pos: SourcePosition, keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
     Ok(ParseRes::ext(match keyword {
         "cmp" => {
             ArithOp::Compare {
@@ -56,7 +57,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Add requires 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Add requires 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -79,7 +80,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Sub requires 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Sub requires 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -102,7 +103,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Mul requires 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Mul requires 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -129,7 +130,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("DivR requires 3 or 4 arguments".into()));
+                    return Err(CrsnError::Parse("DivR requires 3 or 4 arguments".into(), pos));
                 }
             }
         }
@@ -155,7 +156,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Div requires 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Div requires 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -179,7 +180,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Mod requires 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Mod requires 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -202,7 +203,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("And requires 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("And requires 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -225,7 +226,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Or requires 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Or requires 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -248,7 +249,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Xor requires 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Xor requires 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -269,7 +270,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Cpl requires 1 or 2 arguments".into()));
+                    return Err(CrsnError::Parse("Cpl requires 1 or 2 arguments".into(), pos));
                 }
             }
         }
@@ -300,7 +301,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Rol requires 1, 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Rol requires 1, 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -331,7 +332,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Ror requires 1, 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Ror requires 1, 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -362,7 +363,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Lsl requires 1, 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Lsl requires 1, 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -393,7 +394,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Lsr requires 1, 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Lsr requires 1, 2 or 3 arguments".into(), pos));
                 }
             }
         }
@@ -424,7 +425,7 @@ pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<Pars
                     }
                 }
                 _ => {
-                    return Err(CrsnError::Parse("Asr requires 1, 2 or 3 arguments".into()));
+                    return Err(CrsnError::Parse("Asr requires 1, 2 or 3 arguments".into(), pos));
                 }
             }
         }

crsn_screen/src/lib.rs

@@ -5,6 +5,7 @@ use crsn::asm::error::CrsnError;
 use crsn::asm::instr::op::OpKind;
 use crsn::asm::parse::arg_parser::TokenParser;
 use crsn::module::{CrsnExtension, ParseRes};
+use crsn::sexp::SourcePosition;
 
 mod defs;
 mod parse;
@@ -24,7 +25,7 @@ impl CrsnExtension for ScreenOps {
         "screen"
     }
 
-    fn parse_op<'a>(&self, keyword: &str, args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
+    fn parse_op<'a>(&self, pos: SourcePosition, keyword: &str, args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
-        parse::parse(keyword, args)
+        parse::parse(pos, keyword, args)
     }
 }

crsn_screen/src/parse.rs

@@ -5,8 +5,9 @@ use crsn::asm::parse::arg_parser::TokenParser;
 use crsn::module::ParseRes;
 
 use crate::defs::ScreenOp;
+use crsn::sexp::SourcePosition;
 
-pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
+pub(crate) fn parse<'a>(pos: SourcePosition, keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
     Ok(ParseRes::ext(match keyword {
         "sc-init" => {
             ScreenOp::ScreenInit {

crsn_stacks/src/lib.rs

@@ -5,6 +5,7 @@ use crsn::asm::parse::arg_parser::TokenParser;
 use crsn::module::{CrsnExtension, ParseRes};
 use crsn::runtime::fault::Fault;
 use crsn::runtime::run_thread::{RunState, ThreadInfo};
+use crsn::sexp::SourcePosition;
 
 mod defs;
 mod parse;
@@ -24,8 +25,8 @@ impl CrsnExtension for StackOps {
         "stacks"
     }
 
-    fn parse_op<'a>(&self, keyword: &str, args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
+    fn parse_op<'a>(&self, pos: SourcePosition, keyword: &str, args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
-        parse::parse(keyword, args)
+        parse::parse(pos, keyword, args)
     }
 
     fn drop_obj(&self, _ti: &ThreadInfo, state: &mut RunState, handle: Value) -> Result<Option<()>, Fault> {

crsn_stacks/src/parse.rs

@@ -4,8 +4,9 @@ use crsn::asm::parse::arg_parser::TokenParser;
 use crsn::module::ParseRes;
 
 use crate::defs::StackOp;
+use crsn::sexp::SourcePosition;
 
-pub(crate) fn parse<'a>(keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
+pub(crate) fn parse<'a>(pos: SourcePosition, keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
     Ok(ParseRes::ext(match keyword {
         "stack" => {
             StackOp::NewStack {

lib/spanned_sexp/src/error.rs

@@ -9,7 +9,7 @@ pub struct Error {
 }
 
 /// Position in the input string
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Clone, Default)]
 pub struct SourcePosition {
     /// The line number on which the error occurred.
     pub line: usize,
@@ -76,10 +76,10 @@ pub(crate) fn err<T>(message: &'static str, s: &str, pos: &usize) -> ERes<T> {
 }
 
 /// Build a span
-pub(crate) fn spos(s: &str, pos: &usize) -> Option<Box<SourcePosition>> {
+pub(crate) fn spos(s: &str, pos: &usize) -> SourcePosition {
     if *pos >= s.len() {
-        None
+        Default::default()
     } else {
-        Some(Box::new(get_line_and_column(s, *pos)))
+        get_line_and_column(s, *pos)
     }
 }

lib/spanned_sexp/src/lib.rs

@@ -2,7 +2,6 @@
 //! Use `parse` to get an s-expression from its string representation, and the
 //! `Display` trait to serialize it, potentially by doing `sexp.to_string()`.
 
-#![deny(missing_docs)]
 #![deny(unsafe_code)]
 
 #[macro_use]
@@ -38,9 +37,33 @@ pub enum Atom {
 #[derive(Clone)]
 pub enum Sexp {
     /// Atom
-    Atom(Atom, Option<Box<SourcePosition>>),
+    Atom(Atom, SourcePosition),
     /// List of expressions
-    List(Vec<Sexp>, Option<Box<SourcePosition>>),
+    List(Vec<Sexp>, SourcePosition),
+}
+
+impl Sexp {
+    pub fn pos(&self) -> &SourcePosition {
+        match self {
+            Sexp::List(_, pos) | Sexp::Atom(_, pos) => pos
+        }
+    }
+
+    /// Check fi thsi Sexp is an atom
+    pub fn is_atom(&self) -> bool {
+        match self {
+            Sexp::Atom(_, _) => true,
+            _ => false,
+        }
+    }
+
+    /// Check fi thsi Sexp is a list
+    pub fn is_list(&self) -> bool {
+        match self {
+            Sexp::List(_, _) => true,
+            _ => false,
+        }
+    }
 }
 
 impl PartialEq for Sexp {
@@ -207,22 +230,22 @@ fn parse_sexp(s: &str, pos: &mut usize) -> ERes<Sexp> {
 
 /// Constructs an atomic s-expression from a string.
 pub fn atom_s(s: &str) -> Sexp {
-    Sexp::Atom(Atom::S(s.to_owned()), None)
+    Sexp::Atom(Atom::S(s.to_owned()), Default::default())
 }
 
 /// Constructs an atomic s-expression from an int.
 pub fn atom_i(i: i64) -> Sexp {
-    Sexp::Atom(Atom::I(i), None)
+    Sexp::Atom(Atom::I(i), Default::default())
 }
 
 /// Constructs an atomic s-expression from a float.
 pub fn atom_f(f: f64) -> Sexp {
-    Sexp::Atom(Atom::F(f), None)
+    Sexp::Atom(Atom::F(f), Default::default())
 }
 
 /// Constructs a list s-expression given a slice of s-expressions.
 pub fn list(xs: &[Sexp]) -> Sexp {
-    Sexp::List(xs.to_owned(), None)
+    Sexp::List(xs.to_owned(), Default::default())
 }
 
 /// Reads an s-expression out of a `&str`.