diff --git a/Cargo.toml b/Cargo.toml
index 5929391..8ea7461 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -32,6 +32,10 @@ itertools = "0.8.2"
 contracts = "0.6.3"
 bimap = "0.6.3"
 log = "0.4"
+utf8-chars = "3.0.2"
+
+[dependencies.dsn_derive]
+path = "macro/dsn_derive"
 
 [dependencies.geo]
 version = "0.25.1"
diff --git a/macro/dsn_derive/Cargo.toml b/macro/dsn_derive/Cargo.toml
new file mode 100644
index 0000000..0ee0688
--- /dev/null
+++ b/macro/dsn_derive/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "dsn_derive"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1.0.79"
+quote = "1.0.35"
+syn = "2.0.55"
diff --git a/macro/dsn_derive/src/lib.rs b/macro/dsn_derive/src/lib.rs
new file mode 100644
index 0000000..14915b2
--- /dev/null
+++ b/macro/dsn_derive/src/lib.rs
@@ -0,0 +1,40 @@
+use proc_macro::TokenStream;
+use syn::{DeriveInput, Attribute, LitStr};
+
+mod read;
+mod write;
+
+#[proc_macro_derive(ReadDsn, attributes(opt, anon, vec, anon_vec))]
+pub fn derive_read(input: TokenStream)
+    -> TokenStream
+{
+    let input = syn::parse_macro_input!(input as DeriveInput);
+    read::impl_read(&input).into()
+}
+
+#[proc_macro_derive(WriteDsn, attributes(anon))]
+pub fn derive_write(input: TokenStream)
+    -> TokenStream
+{
+    let input = syn::parse_macro_input!(input as DeriveInput);
+    write::impl_write(&input).into()
+}
+
+fn attr_present(attrs: &Vec<Attribute>, name: &str) -> bool {
+    attrs
+        .iter()
+        .find(|attr| attr.path().is_ident(name))
+        .is_some()
+}
+
+fn attr_content(attrs: &Vec<Attribute>, name: &str) -> Option<String> {
+    attrs
+        .iter()
+        .find(|attr| attr.path().is_ident(name))
+        .and_then(|attr| Some(attr
+            .parse_args::<LitStr>()
+            .expect("string literal")
+            .value()
+        ))
+}
+
diff --git a/macro/dsn_derive/src/read.rs b/macro/dsn_derive/src/read.rs
new file mode 100644
index 0000000..cd44a81
--- /dev/null
+++ b/macro/dsn_derive/src/read.rs
@@ -0,0 +1,84 @@
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{Data, DeriveInput, Fields, Field};
+use syn::Type::Path;
+use syn::ext::IdentExt;
+
+use crate::attr_present;
+use crate::attr_content;
+
+pub fn impl_read(input: &DeriveInput) -> TokenStream {
+    let name = &input.ident;
+    let body = impl_body(&input.data);
+
+    quote! {
+        impl<R: std::io::BufRead> ReadDsn<R> for #name {
+            fn read_dsn(tokenizer: &mut ListTokenizer<R>)
+                 -> Result<Self, ParseError>
+            {
+                #body
+            }
+        }
+    }
+}
+
+fn impl_body(data: &Data) -> TokenStream {
+    match data {
+        Data::Struct(data) => {
+            match &data.fields {
+                Fields::Named(fields) => {
+                    let fields = fields.named.iter().map(|field| {
+                        impl_field(field)
+                    });
+
+                    quote! {
+                        Ok(Self {
+                            #(#fields)*
+                        })
+                    }
+                }
+                _ => unimplemented!()
+            }
+        }
+        Data::Enum(_data) => {
+            todo!();
+        }
+        _ => unimplemented!()
+    }
+}
+
+fn impl_field(field: &Field) -> TokenStream {
+    let name = &field.ident;
+    let name_str = name.as_ref().expect("field name").unraw();
+
+    if attr_present(&field.attrs, "anon") {
+        quote! {
+            #name: tokenizer.read_value()?,
+        }
+    } else if let Some(dsn_name) = attr_content(&field.attrs, "vec") {
+        quote! {
+            #name: tokenizer.read_named_array(#dsn_name)?,
+        }
+    } else if attr_present(&field.attrs, "anon_vec") {
+        quote! {
+            #name: tokenizer.read_array()?,
+        }
+    } else {
+        if let Path(type_path) = &field.ty {
+            let segments = &type_path.path.segments;
+            if segments.len() == 1 {
+                let ident = &segments.first().unwrap().ident;
+                if ident == "Option" {
+                    return quote! {
+                        #name: tokenizer.read_optional(stringify!(#name_str))?,
+                    }
+                }
+            }
+        }
+
+        quote! {
+            #name: tokenizer.read_named(stringify!(#name_str))?,
+        }
+    }
+}
+
diff --git a/macro/dsn_derive/src/write.rs b/macro/dsn_derive/src/write.rs
new file mode 100644
index 0000000..6e9cf24
--- /dev/null
+++ b/macro/dsn_derive/src/write.rs
@@ -0,0 +1,84 @@
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{Data, DeriveInput, Fields, Field};
+use syn::Type::Path;
+use syn::ext::IdentExt;
+
+use crate::attr_present;
+use crate::attr_content;
+
+pub fn impl_write(input: &DeriveInput) -> TokenStream {
+    let name = &input.ident;
+
+    let body = impl_body(&input.data);
+
+    quote! {
+        impl<W: std::io::Write> WriteDsn<W> for #name {
+            fn write_dsn(&self, writer: &mut ListWriter<W>)
+                -> std::io::Result<()>
+            {
+                #body
+            }
+        }
+    }
+}
+
+fn impl_body(data: &Data) -> TokenStream {
+    match data {
+        Data::Struct(data) => {
+            match &data.fields {
+                Fields::Named(fields) => {
+                    let fields = fields.named.iter().map(|field| {
+                        impl_field(field)
+                    });
+
+                    quote! {
+                        #(#fields)* 
+
+                        Ok(())
+                    }
+                }
+                _ => unimplemented!()
+            }
+        }
+        _ => unimplemented!()
+    }
+}
+
+fn impl_field(field: &Field) -> TokenStream {
+    let name = &field.ident;
+    let name_str = name.as_ref().expect("field name").unraw();
+
+    if attr_present(&field.attrs, "anon") {
+        quote! {
+            writer.write_value(&self.#name)?;
+        }
+    } else if let Some(dsn_name) = attr_content(&field.attrs, "vec") {
+        quote! {
+            writer.write_named_array(#dsn_name, &self.#name)?;
+        }
+    } else if attr_present(&field.attrs, "anon_vec") {
+        quote! {
+            writer.write_array(&self.#name)?;
+        }
+
+    } else {
+        if let Path(type_path) = &field.ty {
+            let segments = &type_path.path.segments;
+            if segments.len() == 1 {
+                let ident = &segments.first().unwrap().ident;
+                if ident == "Option" {
+                    return quote! {
+                        writer.write_optional(stringify!(#name_str), &self.#name)?;
+                    }
+                }
+            }
+        }
+
+        quote! {
+            writer.write_named(stringify!(#name_str), &self.#name)?;
+        }
+    }
+}
+
+
diff --git a/src/dsn/common.rs b/src/dsn/common.rs
new file mode 100644
index 0000000..6540f86
--- /dev/null
+++ b/src/dsn/common.rs
@@ -0,0 +1,58 @@
+use dsn_derive::ReadDsn;
+
+use super::structure2::*;
+use super::read::{ListTokenizer, ReadDsn, ParseError};
+use super::write::{ListWriter, WriteDsn};
+
+pub enum ListToken {
+    Start { name: String },
+    Leaf { value: String },
+    End,
+}
+
+impl ListToken {
+    pub fn expect_start(self, name: &'static str) -> Result<(), ParseError> {
+        if let Self::Start { name: actual_name } = self {
+            if name == actual_name {
+                Ok(())
+            } else {
+                Err(ParseError::ExpectedStartOfList(name))
+            }
+        } else {
+            Err(ParseError::ExpectedStartOfList(name))
+        }
+    }
+
+    pub fn expect_any_start(self) -> Result<String, ParseError> {
+        if let Self::Start { name } = self {
+            Ok(name)
+        } else {
+            Err(ParseError::ExpectedStartOfList(""))
+        }
+    }
+
+    pub fn expect_leaf(self) -> Result<String, ParseError> {
+        if let Self::Leaf { value } = self {
+            Ok(value)
+        } else {
+            Err(ParseError::Expected("leaf value"))
+        }
+    }
+
+    pub fn expect_end(self) -> Result<(), ParseError>  {
+        if let Self::End = self {
+            Ok(())
+        } else {
+            Err(ParseError::Expected("end of list"))
+        }
+    }
+
+    pub fn len(&self) -> usize {
+        match &self {
+            Self::Start { name } => 1 + name.len(),
+            Self::Leaf { value } => value.len(),
+            Self::End => 1,
+        }
+    }
+}
+
diff --git a/src/dsn/design.rs b/src/dsn/design.rs
index db3049f..6eeccd9 100644
--- a/src/dsn/design.rs
+++ b/src/dsn/design.rs
@@ -32,7 +32,83 @@ pub struct DsnDesign {
 
 impl DsnDesign {
     pub fn load_from_file(filename: &str) -> Result<Self, LoadingError> {
+
+        let file = std::fs::File::open(filename)?;
+        let reader = std::io::BufReader::new(file);
+        let mut list_reader = super::read::ListTokenizer::new(reader);
+
+        let mut dsn = list_reader.read_value::<super::structure2::DsnFile>();
+
+        // TODO: make_board() still uses the old version of structure.rs
+        // so we can't pass the data to topola for real
+
+        if let Ok(dsn) = dsn {
+            use super::structure2::*;
+
+            // (this entire if let block does not belong here)
+
+            let ses_name = filename.replace(".dsn", ".ses");
+            let file2 = std::fs::File::create(ses_name).unwrap();
+            let writer = std::io::BufWriter::new(file2);
+            let mut list_writer = super::write::ListWriter::new(writer);
+
+            let mut net_outs = HashMap::<String, NetOut>::new();
+            for mut wire in dsn.pcb.wiring.wires {
+                // move wires to double check that importing the resulting file into KiCad does something
+                for point in &mut wire.path.coords {
+                    point.x += 1000.0;
+                }
+
+                if let Some(net) = net_outs.get_mut(&wire.net) {
+                    net.wire.push(wire);
+                } else {
+                    net_outs.insert(wire.net.clone(), NetOut {
+                        name: wire.net.clone(),
+                        wire: vec!(wire),
+                        via: Vec::new()
+                    });
+                }
+            }
+            for via in dsn.pcb.wiring.vias {
+                if let Some(net) = net_outs.get_mut(&via.net) {
+                    net.via.push(via);
+                } else {
+                    net_outs.insert(via.net.clone(), NetOut {
+                        name: via.net.clone(),
+                        wire: Vec::new(),
+                        via: vec!(via)
+                    });
+                }
+            }
+
+            // build a basic .ses file from what was loaded
+            let ses = SesFile {
+                session: Session {
+                    id: "ID".to_string(),
+                    routes: Routes {
+                        resolution: Resolution {
+                            unit: "um".into(),
+                            // TODO: why does resolution need to be adjusted from what was imported?
+                            value: 1.0
+                        },
+                        library_out: Library {
+                            images: Vec::new(),
+                            padstacks: dsn.pcb.library.padstacks,
+                        },
+                        network_out: NetworkOut {
+                            net: net_outs.into_values().collect(),
+                        },
+                    }
+                }
+            };
+
+            println!("{:?}", list_writer.write_value(&ses));
+        } else {
+            dbg!(dsn);
+        }
+
         let contents = std::fs::read_to_string(filename)?;
+
         Self::load_from_string(contents)
     }
 
diff --git a/src/dsn/mod.rs b/src/dsn/mod.rs
index f1de5cf..0093e31 100644
--- a/src/dsn/mod.rs
+++ b/src/dsn/mod.rs
@@ -2,3 +2,7 @@ mod de;
 pub mod design;
 pub mod mesadata;
 mod structure;
+mod common;
+mod structure2;
+mod read;
+mod write;
diff --git a/src/dsn/read.rs b/src/dsn/read.rs
new file mode 100644
index 0000000..efdd463
--- /dev/null
+++ b/src/dsn/read.rs
@@ -0,0 +1,312 @@
+use thiserror::Error;
+use utf8_chars::BufReadCharsExt;
+use super::common::ListToken;
+use super::structure2::Parser;
+
+#[derive(Error, Debug)]
+pub enum ParseError {
+    #[error("unexpected end of file")]
+    Eof,
+    #[error(transparent)]
+    Io(#[from] std::io::Error),
+    #[error("expected {0}")]
+    Expected(&'static str),
+    #[error("expected ({0}")]
+    ExpectedStartOfList(&'static str),
+}
+
+pub trait ReadDsn<R: std::io::BufRead>: Sized {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError>;
+}
+// custom impl feeding the read values back into the tokenizer
+impl<R: std::io::BufRead> ReadDsn<R> for Parser {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        Ok(Self {
+            string_quote: tokenizer
+                .read_optional("string_quote")?
+                .inspect(|v| tokenizer.quote_char = Some(*v)),
+            space_in_quoted_tokens: tokenizer
+                .read_optional("space_in_quoted_tokens")?
+                .inspect(|v| tokenizer.space_in_quoted = *v),
+            host_cad: tokenizer.read_optional("host_cad")?,
+            host_version: tokenizer.read_optional("host_version")?,
+        })
+    }
+}
+
+
+impl<R: std::io::BufRead> ReadDsn<R> for String {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        Ok(tokenizer.consume_token()?.expect_leaf()?)
+    }
+}
+
+impl<R: std::io::BufRead> ReadDsn<R> for char {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        let string = tokenizer.consume_token()?.expect_leaf()?;
+        if string.chars().count() == 1 {
+            Ok(string.chars().next().unwrap())
+        } else {
+            Err(ParseError::Expected("a single character"))
+        }
+    }
+}
+
+impl<R: std::io::BufRead> ReadDsn<R> for bool {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        match tokenizer.consume_token()?.expect_leaf()?.as_str() {
+            "on" => Ok(true),
+            "off" => Ok(false),
+            _ => Err(ParseError::Expected("boolean")),
+        }
+    }
+}
+
+impl<R: std::io::BufRead> ReadDsn<R> for i32 {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        Ok(tokenizer
+            .consume_token()?
+            .expect_leaf()?
+            .parse()
+            .map_err(|_| ParseError::Expected("i32"))?)
+    }
+}
+
+impl<R: std::io::BufRead> ReadDsn<R> for u32 {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        Ok(tokenizer
+            .consume_token()?
+            .expect_leaf()?
+            .parse()
+            .map_err(|_| ParseError::Expected("u32"))?)
+    }
+}
+impl<R: std::io::BufRead> ReadDsn<R> for usize {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        Ok(tokenizer
+            .consume_token()?
+            .expect_leaf()?
+            .parse()
+            .map_err(|_| ParseError::Expected("usize"))?)
+    }
+}
+impl<R: std::io::BufRead> ReadDsn<R> for f32 {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        Ok(tokenizer
+            .consume_token()?
+            .expect_leaf()?
+            .parse()
+            .map_err(|_| ParseError::Expected("f32"))?)
+    }
+}
+
+pub struct ListTokenizer<R: std::io::BufRead> {
+    reader: R,
+    peeked_char: Option<char>,
+    cached_token: Option<ListToken>,
+    space_in_quoted: bool,
+    quote_char: Option<char>,
+    line: usize,
+    column: usize,
+}
+
+impl<R: std::io::BufRead> ListTokenizer<R> {
+    pub fn new(reader: R) -> Self {
+        Self {
+            reader: reader,
+            peeked_char: None,
+            cached_token: None,
+            space_in_quoted: false,
+            quote_char: None,
+            line: 1,
+            column: 0,
+        }
+    }
+
+    fn next_char(&mut self) -> Result<char, ParseError> {
+        let return_chr = if let Some(chr) = self.peeked_char {
+            self.peeked_char = None;
+            chr
+        } else {
+            self.reader.chars().next().ok_or(ParseError::Eof)??
+        };
+
+        if return_chr == '\n' {
+            self.line += 1;
+            self.column = 0;
+        } else {
+            self.column += 1;
+        }
+
+        Ok(return_chr)
+    }
+
+    fn peek_char(&mut self) -> Result<char, ParseError> {
+        if let Some(chr) = self.peeked_char {
+            Ok(chr)
+        } else {
+            let chr = self.reader.chars().next().ok_or(ParseError::Eof)??;
+            self.peeked_char = Some(chr);
+            Ok(chr)
+        }
+    }
+
+    fn skip_whitespace(&mut self) -> Result<(), ParseError> {
+        loop {
+            let chr = self.peek_char()?;
+            if chr == ' ' || chr == '\r' || chr == '\n' {
+                self.next_char().unwrap();
+            } else {
+                return Ok(());
+            }
+        }
+    }
+
+    fn read_string(&mut self) -> Result<String, ParseError> {
+        if let Some(chr) = self.quote_char {
+            if chr == self.peek_char()? {
+                return self.read_quoted();
+            }
+        }
+        self.read_unquoted()
+    }
+
+    fn read_unquoted(&mut self) -> Result<String, ParseError> {
+        let mut string = String::new();
+
+        loop {
+            let chr = self.peek_char()?;
+            if chr == ' ' || chr == '(' || chr == ')' || chr == '\r' || chr == '\n' {
+                break;
+            }
+            string.push(self.next_char().unwrap());
+        }
+
+        if string.is_empty() {
+            Err(ParseError::Expected("string (unquoted)"))
+        } else {
+            Ok(string)
+        }
+    }
+
+    fn read_quoted(&mut self) -> Result<String, ParseError> {
+        let mut string = String::new();
+
+        if self.next_char().unwrap() != self.quote_char.unwrap() {
+            panic!();
+        }
+
+        loop {
+            let chr = self.peek_char()?;
+            if !self.space_in_quoted && chr == ' ' {
+                panic!("found a space inside a quoted string, but file didn't declare this possibility");
+            }
+            if chr == self.quote_char.unwrap() {
+                self.next_char().unwrap();
+                break;
+            }
+            string.push(self.next_char().unwrap());
+        }
+
+        Ok(string)
+    }
+
+    // the following two methods effectively allow 1 token of lookahead
+
+    // returns next token, either a cached one returned earlier or a newly read one
+    pub fn consume_token(&mut self) -> Result<ListToken, ParseError> {
+        // move out of cache if not empty, otherwise consume input
+        // always leaves cache empty
+        if let Some(token) = self.cached_token.take() {
+            Ok(token)
+        } else {
+            let token = self.read_token()?;
+            Ok(token)
+        }
+    }
+
+    // puts a token back into cache, to be consumed by something else
+    pub fn return_token(&mut self, token: ListToken) {
+        self.cached_token = Some(token);
+    }
+
+    fn read_token(&mut self) -> Result<ListToken, ParseError> {
+        self.skip_whitespace()?;
+        let chr = self.peek_char()?;
+        Ok(if chr == '(' {
+            self.next_char().unwrap();
+            self.skip_whitespace()?;
+            ListToken::Start { name: self.read_string()? }
+        } else if chr == ')' {
+            self.next_char().unwrap();
+            ListToken::End
+        } else {
+            ListToken::Leaf { value: self.read_string()? }
+        })
+    }
+
+    pub fn read_value<T: ReadDsn<R>>(&mut self) -> Result<T, ParseError> {
+        T::read_dsn(self)
+    }
+
+    pub fn read_named<T: ReadDsn<R>>(&mut self, name: &'static str) -> Result<T, ParseError> {
+        self.consume_token()?.expect_start(name)?;
+        let value = self.read_value::<T>()?;
+        self.consume_token()?.expect_end()?;
+        Ok(value)
+    }
+
+    pub fn read_optional<T: ReadDsn<R>>(&mut self, name: &'static str) -> Result<Option<T>, ParseError> {
+        let token = self.consume_token()?;
+        if let ListToken::Start { name: ref actual_name } = token {
+            if actual_name == name {
+                let value = self.read_value::<T>()?;
+                self.consume_token()?.expect_end()?;
+                Ok(Some(value))
+            } else {
+                self.return_token(token);
+                Ok(None)
+            }
+        } else {
+            self.return_token(token);
+            Ok(None)
+        }
+    }
+
+    pub fn read_array<T: ReadDsn<R>>(&mut self) -> Result<Vec<T>, ParseError> {
+        let mut array = Vec::<T>::new();
+        loop {
+            let token = self.consume_token()?;
+            if let ListToken::Leaf { .. } = token {
+                self.return_token(token);
+                array.push(self.read_value::<T>()?);
+            } else {
+                self.return_token(token);
+                break
+            }
+        }
+        Ok(array)
+    }
+
+    pub fn read_named_array<T: ReadDsn<R>>(&mut self, name: &'static str) -> Result<Vec<T>, ParseError> {
+        let mut array = Vec::<T>::new();
+        loop {
+            let token = self.consume_token()?;
+            if let ListToken::Start { name: ref actual_name } = token {
+                if actual_name == name {
+                    let value = self.read_value::<T>()?;
+                    self.consume_token()?.expect_end()?;
+                    array.push(value);
+                } else {
+                    self.return_token(token);
+                    break
+                }
+            } else {
+                self.return_token(token);
+                break
+            }
+        }
+        Ok(array)
+    }
+}
+
diff --git a/src/dsn/structure2.rs b/src/dsn/structure2.rs
new file mode 100644
index 0000000..52f3569
--- /dev/null
+++ b/src/dsn/structure2.rs
@@ -0,0 +1,399 @@
+use super::read::ReadDsn;
+use super::write::WriteDsn;
+use dsn_derive::ReadDsn;
+use dsn_derive::WriteDsn;
+use super::common::ListToken;
+use super::read::{ListTokenizer, ParseError};
+use super::write::ListWriter;
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Dummy {}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct SesFile {
+    pub session: Session,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Session {
+    #[anon] pub id: String,
+    pub routes: Routes,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Routes {
+    pub resolution: Resolution,
+    pub library_out: Library,
+    pub network_out: NetworkOut,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct NetworkOut {
+    #[vec("net")]
+    pub net: Vec<NetOut>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct NetOut {
+    #[anon] pub name: String,
+    #[vec("wire")]
+    pub wire: Vec<Wire>,
+    #[vec("via")]
+    pub via: Vec<Via>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct DsnFile {
+    pub pcb: Pcb,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Pcb {
+    #[anon] pub name: String,
+    pub parser: Parser,
+    pub resolution: Resolution,
+    pub unit: String,
+    pub structure: Structure,
+    pub placement: Placement,
+    pub library: Library,
+    pub network: Network,
+    pub wiring: Wiring,
+}
+
+#[derive(WriteDsn, Debug)]
+pub struct Parser {
+    pub string_quote: Option<char>,
+    pub space_in_quoted_tokens: Option<bool>,
+    pub host_cad: Option<String>,
+    pub host_version: Option<String>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Resolution {
+    #[anon] pub unit: String,
+    #[anon] pub value: f32,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Structure {
+    #[vec("layer")]
+    pub layers: Vec<Layer>,
+    pub boundary: Boundary,
+    #[vec("plane")]
+    pub planes: Vec<Plane>,
+    pub via: ViaNames,
+    pub rule: Rule,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Layer {
+    #[anon] pub name: String,
+    pub r#type: String,
+    pub property: Property,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Property {
+    pub index: usize,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Boundary {
+    pub path: Path,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Plane {
+    #[anon] pub net: String,
+    pub polygon: Polygon,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct ViaNames {
+    #[anon_vec]
+    pub names: Vec<String>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Placement {
+    #[vec("component")]
+    pub components: Vec<Component>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Component {
+    #[anon] pub name: String,
+    #[vec("place")]
+    pub places: Vec<Place>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+#[allow(non_snake_case)]
+pub struct Place {
+    #[anon] pub name: String,
+    #[anon] pub x: f32,
+    #[anon] pub y: f32,
+    #[anon] pub side: String,
+    #[anon] pub rotation: f32,
+    pub PN: Option<String>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Library {
+    #[vec("image")]
+    pub images: Vec<Image>,
+    #[vec("padstack")]
+    pub padstacks: Vec<Padstack>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Image {
+    #[anon] pub name: String,
+    #[vec("outline")]
+    pub outlines: Vec<Outline>,
+    #[vec("pin")]
+    pub pins: Vec<Pin>,
+    #[vec("keepout")]
+    pub keepouts: Vec<Keepout>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Outline {
+    pub path: Path,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Pin {
+    #[anon] pub name: String,
+    pub rotate: Option<f32>,
+    #[anon] pub id: String,
+    #[anon] pub x: f32,
+    #[anon] pub y: f32,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Rotate {
+    pub angle: f32,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Keepout {
+    #[anon] pub idk: String,
+    #[anon] pub shape: Shape,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Padstack {
+    #[anon] pub name: String,
+    #[vec("shape")]
+    pub shapes: Vec<Shape>,
+    pub attach: bool,
+}
+
+// TODO: derive for enums if more than this single one is needed
+#[derive(Debug)]
+pub enum Shape {
+    Circle(Circle),
+    Rect(Rect),
+    Path(Path),
+    Polygon(Polygon),
+}
+
+impl<R: std::io::BufRead> ReadDsn<R> for Shape {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        let name = tokenizer.consume_token()?.expect_any_start()?;
+        let value = match name.as_str() {
+            "circle" => Ok(Shape::Circle(tokenizer.read_value()?)),
+            "rect" => Ok(Shape::Rect(tokenizer.read_value()?)),
+            "path" => Ok(Shape::Path(tokenizer.read_value()?)),
+            "polygon" => Ok(Shape::Polygon(tokenizer.read_value()?)),
+            _ => Err(ParseError::Expected("a different keyword")),
+        };
+        tokenizer.consume_token()?.expect_end()?;
+        value
+    }
+}
+
+impl<W: std::io::Write> WriteDsn<W> for Shape {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), std::io::Error> {
+        match self {
+            Self::Circle(inner) => writer.write_named("circle", inner),
+            Self::Rect(inner) => writer.write_named("rect", inner),
+            Self::Path(inner) => writer.write_named("path", inner),
+            Self::Polygon(inner) => writer.write_named("polygon", inner),
+        }
+    }
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Circle {
+    #[anon] pub layer: String,
+    #[anon] pub diameter: u32,
+    #[anon] pub offset: Option<Point>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Network {
+    #[vec("net")]
+    pub nets: Vec<NetPinAssignments>,
+    #[vec("class")]
+    pub classes: Vec<Class>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+// dsn names this "net", but it's a structure unrelated to "net" in wiring or elsewhere
+pub struct NetPinAssignments {
+    #[anon] pub name: String,
+    pub pins: Pins,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Pins {
+    #[anon_vec]
+    pub names: Vec<String>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Class {
+    #[anon]
+    pub name: String,
+    #[anon_vec]
+    pub nets: Vec<String>,
+    pub circuit: Circuit,
+    pub rule: Rule,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Circuit {
+    pub use_via: String,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Wiring {
+    #[vec("wire")]
+    pub wires: Vec<Wire>,
+    #[vec("via")]
+    pub vias: Vec<Via>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Wire {
+    pub path: Path,
+    pub net: String,
+    pub r#type: String,
+}
+
+////////////////////////////////////////////
+// structs that appear in multiple places //
+////////////////////////////////////////////
+
+// This type isn't meant to be deserialized as is (single points are
+// more conveniently represented as fields on the enclosing struct)
+// It exists to give a way to read arrays of coordinates
+// (and enforce that such an array actually contains a whole number of points)
+#[derive(Debug)]
+pub struct Point {
+    pub x: f32,
+    pub y: f32,
+}
+
+// Custom impl for the case described above
+impl<R: std::io::BufRead> ReadDsn<R> for Vec<Point> {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        let mut array = Vec::<Point>::new();
+        loop {
+            let token = tokenizer.consume_token()?;
+            if let ListToken::Leaf { value: ref x } = token {
+                let x = x.parse::<f32>().unwrap();
+                let y = tokenizer.read_value::<f32>()?;
+                array.push(Point { x, y });
+            } else {
+                tokenizer.return_token(token);
+                break
+            }
+        }
+        Ok(array)
+    }
+}
+
+impl<R: std::io::BufRead> ReadDsn<R> for Option<Point> {
+    fn read_dsn(tokenizer: &mut ListTokenizer<R>) -> Result<Self, ParseError> {
+        let token = tokenizer.consume_token()?;
+        if let ListToken::Leaf { value: ref x } = token {
+            let x = x.parse::<f32>().unwrap();
+            let y = tokenizer.read_value::<f32>()?;
+            Ok(Some(Point { x, y }))
+        } else {
+            tokenizer.return_token(token);
+            Ok(None)
+        }
+    }
+}
+
+impl<W: std::io::Write> WriteDsn<W> for Vec<Point> {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), std::io::Error> {
+        for elem in self {
+            writer.write_value(&elem.x)?;
+            writer.write_value(&elem.y)?;
+        }
+        Ok(())
+    }
+}
+
+impl<W: std::io::Write> WriteDsn<W> for Option<Point> {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), std::io::Error> {
+        if let Some(value) = self {
+            writer.write_value(&value.x)?;
+            writer.write_value(&value.y)?;
+        }
+        Ok(())
+    }
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Polygon {
+    #[anon] pub layer: String,
+    #[anon] pub width: f32,
+    #[anon] pub coords: Vec<Point>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Path {
+    #[anon] pub layer: String,
+    #[anon] pub width: f32,
+    #[anon] pub coords: Vec<Point>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Rect {
+    #[anon] pub layer: String,
+    #[anon] pub x1: f32,
+    #[anon] pub y1: f32,
+    #[anon] pub x2: f32,
+    #[anon] pub y2: f32,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Via {
+    #[anon]
+    pub name: String,
+    #[anon]
+    pub x: i32,
+    #[anon]
+    pub y: i32,
+    pub net: String,
+    pub r#type: String,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Rule {
+    pub width: f32,
+    #[vec("clearance")]
+    pub clearances: Vec<Clearance>,
+}
+
+#[derive(ReadDsn, WriteDsn, Debug)]
+pub struct Clearance {
+    #[anon] pub value: f32,
+    pub r#type: Option<String>,
+}
diff --git a/src/dsn/write.rs b/src/dsn/write.rs
new file mode 100644
index 0000000..71ae500
--- /dev/null
+++ b/src/dsn/write.rs
@@ -0,0 +1,182 @@
+use super::common::ListToken;
+use std::io;
+
+pub trait WriteDsn<W: io::Write> {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), io::Error>;
+}
+
+impl<W: io::Write> WriteDsn<W> for char {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), io::Error> {
+        writer.write_leaf(self.to_string())
+    }
+}
+
+impl<W: io::Write> WriteDsn<W> for String {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), io::Error> {
+        let string = if self.len() == 0 {
+            "\"\"".to_string()
+        } else if self.contains(" ")
+               || self.contains("(")
+               || self.contains(")")
+               || self.contains("\n")
+        {
+            format!("\"{}\"", self)
+        } else {
+            self.to_string()
+        };
+        writer.write_leaf(string)
+    }
+}
+
+impl<W: io::Write> WriteDsn<W> for bool {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), io::Error> {
+        writer.write_leaf(match self {
+            true => "on".to_string(),
+            false => "off".to_string(),
+        })
+    }
+}
+
+impl<W: io::Write> WriteDsn<W> for i32 {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), io::Error> {
+        writer.write_leaf(self.to_string())
+    }
+}
+
+impl<W: io::Write> WriteDsn<W> for u32 {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), io::Error> {
+        writer.write_leaf(self.to_string())
+    }
+}
+
+impl<W: io::Write> WriteDsn<W> for usize {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), io::Error> {
+        writer.write_leaf(self.to_string())
+    }
+}
+
+impl<W: io::Write> WriteDsn<W> for f32 {
+    fn write_dsn(&self, writer: &mut ListWriter<W>) -> Result<(), io::Error> {
+        writer.write_leaf(self.to_string())
+    }
+}
+
+pub struct ListWriter<W: io::Write> {
+    writable: W,
+    indent_level: usize,
+    multiline_level: usize,
+    pub line_len: usize,
+}
+
+impl<W: io::Write> ListWriter<W> {
+    pub fn new(writable: W) -> Self {
+        Self {
+            writable,
+            indent_level: 0,
+            multiline_level: 0,
+            line_len: 0,
+        }
+    }
+
+    pub fn write_token(&mut self, token: ListToken) -> Result<(), io::Error> {
+        let len = token.len();
+
+        match token {
+            ListToken::Start { name } => {
+                write!(self.writable,
+                    "\n{}({}",
+                    "  ".repeat(self.indent_level),
+                    name
+                )?;
+                self.multiline_level = self.indent_level;
+                self.line_len = 2 * self.indent_level + len;
+                self.indent_level += 1;
+                Ok(())
+            }
+            ListToken::Leaf { value } => {
+                self.line_len += 1 + len;
+                write!(self.writable, " {}", value)
+            }
+            ListToken::End => {
+                if self.indent_level <= self.multiline_level {
+                    self.indent_level -= 1;
+                    self.line_len = 2 * self.indent_level + len;
+                    write!(self.writable,
+                        "\n{})",
+                        "  ".repeat(self.indent_level)
+                    )
+                } else {
+                    self.indent_level -= 1;
+                    self.line_len += len;
+                    write!(self.writable, ")")
+                }
+            }
+        }
+    }
+
+    pub fn write_leaf(&mut self, value: String) -> Result<(), io::Error> {
+        self.write_token(ListToken::Leaf { value })
+    }
+
+    pub fn write_value<T: WriteDsn<W>>(
+        &mut self,
+        value: &T,
+    ) -> Result<(), io::Error> {
+        value.write_dsn(self)
+    }
+
+    pub fn write_named<T: WriteDsn<W>>(
+        &mut self,
+        name: &'static str,
+        value: &T,
+    )
+        -> Result<(), io::Error>
+    {
+        self.write_token(ListToken::Start { name: name.to_string() } )?;
+        self.write_value(value)?;
+        self.write_token(ListToken::End)?;
+
+        Ok(())
+    }
+
+    pub fn write_optional<T: WriteDsn<W>>(
+        &mut self,
+        name: &'static str,
+        optional: &Option<T>,
+    )
+        -> Result<(), io::Error>
+    {
+        if let Some(value) = optional {
+            self.write_named(name, value)?;
+        }
+
+        Ok(())
+    }
+
+    pub fn write_array<T: WriteDsn<W>>(
+        &mut self,
+        array: &Vec<T>,
+    )
+        -> Result<(), io::Error>
+    {
+        for elem in array {
+            self.write_value(elem)?;
+        }
+
+        Ok(())
+    }
+
+    pub fn write_named_array<T: WriteDsn<W>>(
+        &mut self,
+        name: &'static str,
+        array: &Vec<T>,
+    )
+        -> Result<(), io::Error>
+    {
+        for elem in array {
+            self.write_named(name, elem)?;
+        }
+
+        Ok(())
+    }
+}