diff --git a/mers/Cargo.toml b/mers/Cargo.toml
index 0a7696a..557d6b8 100644
--- a/mers/Cargo.toml
+++ b/mers/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mers"
-version = "0.8.15"
+version = "0.8.16"
 edition = "2021"
 license = "MIT OR Apache-2.0"
 description = "dynamically typed but type-checked programming language"
@@ -12,10 +12,10 @@ repository = "https://github.com/Dummi26/mers"
 
 [features]
 default = ["colored-output"]
-colored-output = ["mers_lib/ecolor-term", "dep:colored"]
+colored-output = ["mers_lib/ecolor-term", "mers_lib/pretty-print", "dep:colored"]
 
 [dependencies]
-mers_lib = "0.8.15"
+mers_lib = "0.8.16"
 # mers_lib = { path = "../mers_lib" }
 clap = { version = "4.3.19", features = ["derive"] }
 colored = { version = "2.1.0", optional = true }
diff --git a/mers/src/main.rs b/mers/src/main.rs
index 00a428a..c59125f 100755
--- a/mers/src/main.rs
+++ b/mers/src/main.rs
@@ -3,8 +3,6 @@ use mers_lib::prelude_compile::*;
 use std::{path::PathBuf, process::exit, sync::Arc};
 
 mod cfg_globals;
-#[cfg(feature = "colored-output")]
-mod pretty_print;
 
 #[derive(Parser)]
 struct Args {
@@ -169,7 +167,7 @@ fn main() {
         }
         #[cfg(feature = "colored-output")]
         Command::PrettyPrint { source } => {
-            pretty_print::pretty_print(get_source(source));
+            mers_lib::pretty_print::pretty_print(get_source(source));
         }
         #[cfg(not(feature = "colored-output"))]
         Command::PrettyPrint { source: _ } => {
diff --git a/mers/src/pretty_print.rs b/mers/src/pretty_print.rs
deleted file mode 100644
index d918e0b..0000000
--- a/mers/src/pretty_print.rs
+++ /dev/null
@@ -1,138 +0,0 @@
-use std::{process::exit, sync::Arc};
-
-use colored::{Color, Colorize};
-use mers_lib::prelude_compile::{parse, Source};
-
-pub fn pretty_print(mut src: Source) {
-    let srca = Arc::new(src.clone());
-    match parse(&mut src, &srca) {
-        Err(e) => {
-            eprintln!("{e:?}");
-            exit(28);
-        }
-        Ok(parsed) => {
-            print_parsed(&srca, parsed.as_ref());
-        }
-    }
-}
-
-const COLOR_COMMENT: Color = Color::BrightBlack;
-const COLOR_VARIABLE: Color = Color::Green;
-const COLOR_VARIABLE_REF: Color = Color::Green;
-const COLOR_IF: Color = Color::Red;
-const COLOR_IF_WITH_ELSE: Color = Color::Red;
-const COLOR_LOOP: Color = Color::Red;
-const COLOR_TUPLE: Color = Color::Blue;
-const COLOR_OBJECT: Color = Color::Blue;
-const COLOR_VALUE: Color = Color::Cyan;
-const COLOR_AS_TYPE: Color = Color::BrightBlack;
-const COLOR_CUSTOM_TYPE: Color = Color::BrightBlack;
-const COLOR_UNKNOWN: Color = Color::White;
-
-fn print_parsed(srca: &Arc<Source>, parsed: &dyn mers_lib::program::parsed::MersStatement) {
-    let mut sections = vec![(COLOR_UNKNOWN, srca.src_og().len())];
-    build_print(&mut sections, srca, parsed);
-    for (start, comment) in srca.comments() {
-        let end = start + comment.len();
-        build_print_insert_color(&mut sections, COLOR_COMMENT, *start, end);
-    }
-    let src = srca.src_og();
-    let mut i = 0;
-    for (clr, end) in sections {
-        print!("{}", src[i..end].color(clr));
-        i = end;
-    }
-    println!();
-}
-fn build_print(
-    sections: &mut Vec<(Color, usize)>,
-    srca: &Arc<Source>,
-    parsed: &dyn mers_lib::program::parsed::MersStatement,
-) {
-    let any = parsed.as_any();
-    let clr = if let Some(v) = any.downcast_ref::<mers_lib::program::parsed::variable::Variable>() {
-        if v.is_ref {
-            COLOR_VARIABLE_REF
-        } else {
-            COLOR_VARIABLE
-        }
-    } else if let Some(v) = any.downcast_ref::<mers_lib::program::parsed::r#if::If>() {
-        if v.on_false.is_some() {
-            COLOR_IF_WITH_ELSE
-        } else {
-            COLOR_IF
-        }
-    } else if let Some(_) = any.downcast_ref::<mers_lib::program::parsed::r#loop::Loop>() {
-        COLOR_LOOP
-    } else if let Some(_) = any.downcast_ref::<mers_lib::program::parsed::tuple::Tuple>() {
-        COLOR_TUPLE
-    } else if let Some(_) = any.downcast_ref::<mers_lib::program::parsed::object::Object>() {
-        COLOR_OBJECT
-    } else if let Some(_) = any.downcast_ref::<mers_lib::program::parsed::value::Value>() {
-        COLOR_VALUE
-    } else if let Some(_) = any.downcast_ref::<mers_lib::program::parsed::as_type::AsType>() {
-        COLOR_AS_TYPE
-    } else if let Some(_) = any.downcast_ref::<mers_lib::program::parsed::custom_type::CustomType>()
-    {
-        COLOR_CUSTOM_TYPE
-    } else {
-        COLOR_UNKNOWN
-    };
-    let range = parsed.source_range();
-    let start = srca.pos_in_og(range.start().pos(), true);
-    let end = srca.pos_in_og(range.end().pos(), false);
-    build_print_insert_color(sections, clr, start, end);
-    for s in parsed.inner_statements() {
-        build_print(sections, srca, s);
-    }
-}
-
-fn build_print_insert_color(
-    sections: &mut Vec<(Color, usize)>,
-    clr: Color,
-    start: usize,
-    end: usize,
-) {
-    let thing_at_my_start = sections.iter().position(|v| v.1 > start);
-    let thing_at_my_end = sections.iter().position(|v| v.1 > end);
-    if let Some(thing_at_my_start) = thing_at_my_start {
-        if let Some(thing_at_my_end) = thing_at_my_end {
-            if thing_at_my_start == thing_at_my_end {
-                let (around_color, around_end) = sections[thing_at_my_start];
-                if around_color != clr {
-                    sections[thing_at_my_start].1 = start;
-                    sections.insert(thing_at_my_start + 1, (clr, end));
-                    sections.insert(thing_at_my_start + 2, (around_color, around_end));
-                    if sections[thing_at_my_start].1
-                        == thing_at_my_start
-                            .checked_sub(1)
-                            .map(|v| sections[v].1)
-                            .unwrap_or(0)
-                    {
-                        // thing at my start now ends at the same place the thing before it ends, so we can remove it
-                        sections.remove(thing_at_my_start);
-                    }
-                }
-            } else {
-                sections[thing_at_my_start].1 = start;
-                sections.insert(thing_at_my_start + 1, (clr, end));
-                for _ in 0..(thing_at_my_end.saturating_sub(thing_at_my_start + 1)) {
-                    sections.remove(thing_at_my_start + 2);
-                }
-            }
-        } else {
-            if sections[thing_at_my_start].0 == clr {
-                sections[thing_at_my_start].1 = end;
-            } else {
-                sections[thing_at_my_start].1 = start;
-                sections.push((clr, end));
-            }
-        }
-    } else {
-        if let Some(last) = sections.last_mut().filter(|v| v.0 == clr) {
-            last.1 = end;
-        } else {
-            sections.push((clr, end));
-        }
-    }
-}
diff --git a/mers_lib/Cargo.toml b/mers_lib/Cargo.toml
index 39199e7..e0c710f 100755
--- a/mers_lib/Cargo.toml
+++ b/mers_lib/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mers_lib"
-version = "0.8.15"
+version = "0.8.16"
 edition = "2021"
 license = "MIT OR Apache-2.0"
 description = "library to use the mers language in other projects"
@@ -17,7 +17,12 @@ run = []
 
 # color features are used when formatting error messages.
 ecolor-term = ["dep:colored"]
+ecolor-html = ["dep:html-escape"]
+
+# pretty-print requires ecolor-term, but this is not listed here because I want people to explicitly opt-in to the extra `colored` dependency via the ecolor-term feature.
+pretty-print = []
 
 [dependencies]
-colored = { version = "2.1.0", optional = true }
 line-span = "0.1.5"
+colored = { version = "2.1.0", optional = true }
+html-escape = { version = "0.2.13", optional = true }
diff --git a/mers_lib/src/errors/mod.rs b/mers_lib/src/errors/mod.rs
index 777d92d..829cbac 100644
--- a/mers_lib/src/errors/mod.rs
+++ b/mers_lib/src/errors/mod.rs
@@ -8,6 +8,9 @@ use line_span::LineSpans;
 
 #[cfg(feature = "parse")]
 use crate::parsing::Source;
+use crate::theme::ThemeGen;
+
+pub mod themes;
 
 #[derive(Clone, Copy, Debug)]
 pub struct SourcePos(pub(crate) usize);
@@ -62,6 +65,9 @@ pub enum EColor {
     BackslashEscapeUnknown,
     BackslashEscapeEOF,
     StringEOF,
+    TypeEOF,
+    /// `&[Int/String` (notice the missing `]`)
+    BracketedRefTypeNoClosingBracket,
     IfConditionNotBool,
     ChainWithNonFunction,
     Function,
@@ -92,115 +98,24 @@ pub enum EColor {
     InCodePositionLine,
 }
 
-pub trait Theme<T> {
-    fn color(&self, text: &str, color: EColor, t: &mut T);
-}
-pub trait ThemeTo<T>: Theme<T> {
-    fn color_to(&self, text: &str, color: EColor) -> T;
-}
-impl<T: Theme<String> + ?Sized> ThemeTo<String> for T {
-    fn color_to(&self, text: &str, color: EColor) -> String {
-        let mut t = String::new();
-        self.color(text, color, &mut t);
-        t
-    }
-}
+pub trait ETheme: ThemeGen<C = EColor, T = String> {}
+impl<T: ThemeGen<C = EColor, T = String>> ETheme for T {}
+
 pub fn colorize_str(
     message: &Vec<(String, Option<EColor>)>,
-    theme: &(impl Theme<String> + ?Sized),
+    theme: &(impl ETheme + ?Sized),
 ) -> String {
     let mut t = String::new();
-    colorize_gen(message, &mut t, |t, a| a.push_str(t), theme);
-    t
-}
-pub fn colorize_gen<T>(
-    message: &Vec<(String, Option<EColor>)>,
-    t: &mut T,
-    direct: impl Fn(&str, &mut T),
-    theme: &(impl Theme<T> + ?Sized),
-) {
     for (text, color) in message {
         if let Some(color) = *color {
-            theme.color(text, color, t)
+            theme.color(text, color, &mut t)
         } else {
-            direct(text, t)
+            theme.nocolor(text, &mut t)
         }
     }
+    t
 }
 
-pub struct NoTheme;
-impl Theme<String> for NoTheme {
-    fn color(&self, text: &str, _color: EColor, t: &mut String) {
-        t.push_str(text);
-    }
-}
-
-#[cfg(feature = "ecolor-term")]
-pub struct TermDefaultTheme;
-#[cfg(feature = "ecolor-term")]
-impl Theme<String> for TermDefaultTheme {
-    fn color(&self, text: &str, color: EColor, t: &mut String) {
-        use colored::{Color, Colorize};
-        t.push_str(
-            &text
-                .color(match color {
-                    EColor::Indent(n) => match n % 6 {
-                        0 => Color::Red,
-                        1 => Color::Green,
-                        2 => Color::Yellow,
-                        3 => Color::Blue,
-                        4 => Color::Magenta,
-                        _ => Color::Cyan,
-                    },
-
-                    EColor::UnknownVariable => Color::Red,
-
-                    EColor::WhitespaceAfterHashtag => Color::Red,
-                    EColor::HashUnknown => Color::Red,
-                    EColor::HashIncludeCantLoadFile => Color::Red,
-                    EColor::HashIncludeNotAString => Color::Red,
-                    EColor::HashIncludeErrorInIncludedFile => Color::Red,
-
-                    EColor::BackslashEscapeUnknown => Color::Red,
-                    EColor::BackslashEscapeEOF => Color::Red,
-                    EColor::StringEOF => Color::Red,
-
-                    EColor::IfConditionNotBool => Color::Red,
-                    EColor::ChainWithNonFunction => Color::Yellow,
-
-                    EColor::Function => Color::BrightMagenta,
-                    EColor::FunctionArgument => Color::BrightBlue,
-
-                    EColor::InitFrom
-                    | EColor::AssignFrom
-                    | EColor::AsTypeStatementWithTooBroadType => Color::BrightCyan,
-                    EColor::InitTo | EColor::AssignTo | EColor::AsTypeTypeAnnotation => {
-                        Color::Green
-                    }
-                    EColor::AssignTargetNonReference => Color::BrightYellow,
-
-                    EColor::BadCharInTupleType => Color::Red,
-                    EColor::BadCharInFunctionType => Color::Red,
-                    EColor::BadTypeFromParsed => Color::Blue,
-                    EColor::TypeAnnotationNoClosingBracket => Color::Blue,
-
-                    EColor::TryBadSyntax => Color::Red,
-                    EColor::TryNoFunctionFound => Color::Red,
-                    EColor::TryNotAFunction => Color::Red,
-                    EColor::TryUnusedFunction1 => Color::Red,
-                    EColor::TryUnusedFunction2 => Color::BrightRed,
-                    EColor::CustomTypeTestFailed => Color::BrightRed,
-
-                    EColor::StacktraceDescend => Color::Yellow,
-                    EColor::StacktraceDescendHashInclude => Color::Red,
-                    EColor::MaximumRuntimeExceeded => Color::BrightYellow,
-
-                    EColor::InCodePositionLine => Color::BrightBlack,
-                })
-                .to_string(),
-        );
-    }
-}
 #[derive(Clone)]
 pub enum CheckErrorComponent {
     Message(Vec<(String, Option<EColor>)>),
@@ -211,7 +126,7 @@ pub enum CheckErrorComponent {
 pub struct CheckErrorHRConfig {
     color_index_ptr: Rc<AtomicU32>,
     color_index: u32,
-    theme: Rc<dyn Theme<String>>,
+    theme: Rc<dyn ETheme>,
     is_inner: bool,
     style: u8,
     idt_start: String,
@@ -335,7 +250,7 @@ impl CheckErrorHRConfig {
 #[cfg(feature = "parse")]
 pub struct CheckErrorDisplay<'a> {
     e: &'a CheckError,
-    theme: Rc<dyn Theme<String>>,
+    theme: Rc<dyn ETheme>,
     pub show_comments: bool,
 }
 #[cfg(feature = "parse")]
@@ -409,7 +324,7 @@ impl CheckError {
         self.add_mut(CheckErrorComponent::Source(s))
     }
     #[cfg(feature = "parse")]
-    pub fn display<'a>(&'a self, theme: impl Theme<String> + 'static) -> CheckErrorDisplay<'a> {
+    pub fn display<'a>(&'a self, theme: impl ETheme + 'static) -> CheckErrorDisplay<'a> {
         CheckErrorDisplay {
             e: self,
             theme: Rc::new(theme),
@@ -419,13 +334,13 @@ impl CheckError {
     /// Like `display`, but doesn't use any theme (doesn't colorize its output)
     #[cfg(feature = "parse")]
     pub fn display_notheme<'a>(&'a self) -> CheckErrorDisplay<'a> {
-        self.display(NoTheme)
+        self.display(themes::NoTheme)
     }
     /// Like `display`, but uses the default terminal theme
     #[cfg(feature = "parse")]
     #[cfg(feature = "ecolor-term")]
     pub fn display_term<'a>(&'a self) -> CheckErrorDisplay<'a> {
-        self.display(TermDefaultTheme)
+        self.display(themes::TermDefaultTheme)
     }
     /// will, unless empty, end in a newline
     #[cfg(feature = "parse")]
@@ -435,7 +350,7 @@ impl CheckError {
         cfg: &CheckErrorHRConfig,
     ) -> std::fmt::Result {
         const ADD_RIGHT_BITS: bool = false;
-        use crate::parsing::SourceFrom;
+        use crate::{parsing::SourceFrom, theme::ThemeTo};
 
         let len = self.0.len();
         for (i, component) in self.0.iter().enumerate() {
diff --git a/mers_lib/src/errors/themes.rs b/mers_lib/src/errors/themes.rs
new file mode 100644
index 0000000..f33ca58
--- /dev/null
+++ b/mers_lib/src/errors/themes.rs
@@ -0,0 +1,177 @@
+use super::{EColor, ThemeGen};
+
+pub struct NoTheme;
+impl ThemeGen for NoTheme {
+    type C = EColor;
+    type T = String;
+    fn color(&self, text: &str, _color: EColor, t: &mut String) {
+        self.nocolor(text, t);
+    }
+    fn nocolor(&self, text: &str, t: &mut String) {
+        t.push_str(text);
+    }
+}
+
+/// converts an `EColor` to the color type you need for your theme.
+/// This theme is optimized for ANSI terminal colors,
+/// as most of mers' colored output will be printed to a terminal.
+pub fn default_theme<C>(
+    color: EColor,
+    gray: C,
+    red: C,
+    red_bright: C,
+    green: C,
+    green_bright: C,
+    yellow: C,
+    yellow_bright: C,
+    blue: C,
+    blue_bright: C,
+    magenta: C,
+    magenta_bright: C,
+    cyan: C,
+    cyan_bright: C,
+) -> Option<C> {
+    if let Indent(n) = color {
+        return Some(match n % 7 {
+            1 => red,
+            2 => green,
+            3 => yellow,
+            4 => blue,
+            5 => magenta,
+            6 => cyan,
+            _ => return None,
+        });
+    }
+    let hard_err = red;
+    let type_right = blue;
+    let type_wrong = magenta;
+    let type_wrong_b = magenta_bright;
+    let function = blue_bright; // used in combination with TYPE_WRONG
+    let missing = cyan;
+    let runtime = yellow;
+    let runtime_b = yellow_bright;
+    let unused = green;
+    let unused_b = green_bright;
+    drop(red_bright);
+    drop(cyan_bright);
+    use EColor::*;
+    Some(match color {
+        Indent(_) => unreachable!(),
+
+        // macros (#...)
+        WhitespaceAfterHashtag
+        | HashUnknown
+        | HashIncludeCantLoadFile
+        | HashIncludeNotAString
+        | HashIncludeErrorInIncludedFile
+        | StacktraceDescendHashInclude => hard_err,
+
+        // -- bad syntax --
+        UnknownVariable => hard_err,
+        BackslashEscapeUnknown => hard_err,
+        BackslashEscapeEOF | StringEOF | TypeEOF => missing,
+        BadCharInTupleType => hard_err,
+        BadCharInFunctionType => hard_err,
+        TryBadSyntax => hard_err,
+        TypeAnnotationNoClosingBracket | BracketedRefTypeNoClosingBracket => missing,
+
+        BadTypeFromParsed => type_wrong_b,
+
+        // -- type-errors --
+        IfConditionNotBool => type_wrong,
+        TryNoFunctionFound => type_wrong_b,
+        TryNotAFunction => type_wrong,
+        TryUnusedFunction1 => unused,
+        TryUnusedFunction2 => unused_b,
+
+        CustomTypeTestFailed => hard_err,
+
+        ChainWithNonFunction => type_wrong,
+
+        AssignTargetNonReference => type_wrong,
+
+        Function => function,
+        FunctionArgument => type_wrong,
+
+        InitFrom | AssignFrom | AsTypeStatementWithTooBroadType => type_wrong,
+        InitTo | AssignTo | AsTypeTypeAnnotation => type_right,
+
+        // -- runtime-errors --
+        StacktraceDescend => runtime,
+        MaximumRuntimeExceeded => runtime_b,
+
+        InCodePositionLine => gray,
+    })
+}
+
+#[cfg(feature = "ecolor-term")]
+pub struct TermDefaultTheme;
+#[cfg(feature = "ecolor-term")]
+impl ThemeGen for TermDefaultTheme {
+    type C = EColor;
+    type T = String;
+    fn color(&self, text: &str, color: EColor, t: &mut String) {
+        use colored::Color::*;
+        if let Some(color) = default_theme(
+            color,
+            BrightBlack,
+            Red,
+            BrightRed,
+            Green,
+            BrightGreen,
+            Yellow,
+            BrightYellow,
+            Blue,
+            BrightBlue,
+            Magenta,
+            BrightMagenta,
+            Cyan,
+            BrightCyan,
+        ) {
+            use colored::Colorize;
+            t.push_str(&text.color(color).to_string());
+        } else {
+            self.nocolor(text, t)
+        }
+    }
+    fn nocolor(&self, text: &str, t: &mut String) {
+        t.push_str(text);
+    }
+}
+
+#[cfg(feature = "ecolor-html")]
+pub struct HtmlDefaultTheme;
+#[cfg(feature = "ecolor-html")]
+impl ThemeGen for HtmlDefaultTheme {
+    type C = EColor;
+    type T = String;
+    fn color(&self, text: &str, color: EColor, t: &mut String) {
+        if let Some(color) = default_theme(
+            color,
+            "Gray",
+            "Crimson",
+            "Red",
+            "Green",
+            "LimeGreen",
+            "Gold",
+            "Yellow",
+            "RoyalBlue",
+            "DeepSkyBlue",
+            "Purple",
+            "Orchid",
+            "DarkCyan",
+            "Turquoise",
+        ) {
+            t.push_str("<span style=\"color:");
+            t.push_str(color);
+            t.push_str(";\">");
+            html_escape::encode_text_to_string(text, t);
+            t.push_str("</span>");
+        } else {
+            html_escape::encode_text_to_string(text, t);
+        }
+    }
+    fn nocolor(&self, text: &str, t: &mut String) {
+        t.push_str(text);
+    }
+}
diff --git a/mers_lib/src/lib.rs b/mers_lib/src/lib.rs
index f717bb9..a7108c4 100755
--- a/mers_lib/src/lib.rs
+++ b/mers_lib/src/lib.rs
@@ -7,7 +7,10 @@ pub mod info;
 /// parser implementation.
 #[cfg(feature = "parse")]
 pub mod parsing;
+#[cfg(feature = "pretty-print")]
+pub mod pretty_print;
 pub mod program;
+pub mod theme;
 
 #[cfg(feature = "parse")]
 pub mod prelude_compile {
diff --git a/mers_lib/src/parsing/mod.rs b/mers_lib/src/parsing/mod.rs
index 15d4b38..6805be8 100755
--- a/mers_lib/src/parsing/mod.rs
+++ b/mers_lib/src/parsing/mod.rs
@@ -308,6 +308,9 @@ impl Source {
         line
     }
 
+    pub fn get_pos_last_char(&self) -> SourcePos {
+        SourcePos(self.i.saturating_sub(1))
+    }
     pub fn get_pos(&self) -> SourcePos {
         SourcePos(self.i)
     }
diff --git a/mers_lib/src/parsing/statements.rs b/mers_lib/src/parsing/statements.rs
index 03a7d0a..71e2228 100755
--- a/mers_lib/src/parsing/statements.rs
+++ b/mers_lib/src/parsing/statements.rs
@@ -555,7 +555,7 @@ pub fn parse_string(
     srca: &Arc<Source>,
     double_quote: SourcePos,
 ) -> Result<String, CheckError> {
-    parse_string_custom_end(src, srca, double_quote, '"', '"')
+    parse_string_custom_end(src, srca, double_quote, '"', '"', "", EColor::StringEOF)
 }
 pub fn parse_string_custom_end(
     src: &mut Source,
@@ -563,6 +563,8 @@ pub fn parse_string_custom_end(
     opening: SourcePos,
     opening_char: char,
     closing_char: char,
+    string_prefix: &str,
+    eof_color: EColor,
 ) -> Result<String, CheckError> {
     let mut s = String::new();
     loop {
@@ -602,13 +604,13 @@ pub fn parse_string_custom_end(
             return Err(CheckError::new()
                 .src(vec![(
                     (opening, src.get_pos(), srca).into(),
-                    Some(EColor::StringEOF),
+                    Some(eof_color),
                 )])
                 .msg_str(format!(
-                    "EOF in string literal{}",
+                    "EOF in {string_prefix}string literal{}",
                     if closing_char != '"' {
                         format!(
-                            "{opening_char}...{closing_char} (end string with '{closing_char}')"
+                            " {opening_char}...{closing_char} (end string with '{closing_char}')"
                         )
                     } else {
                         String::new()
diff --git a/mers_lib/src/parsing/types.rs b/mers_lib/src/parsing/types.rs
index 9767e45..35ff7f9 100755
--- a/mers_lib/src/parsing/types.rs
+++ b/mers_lib/src/parsing/types.rs
@@ -24,6 +24,7 @@ pub fn parse_single_type(src: &mut Source, srca: &Arc<Source>) -> Result<ParsedT
     Ok(match src.peek_char() {
         // Reference
         Some('&') => {
+            let pos_in_src = src.get_pos();
             src.next_char();
             if let Some('[') = src.peek_char() {
                 src.next_char();
@@ -35,9 +36,14 @@ pub fn parse_single_type(src: &mut Source, srca: &Arc<Source>) -> Result<ParsedT
                     } else {
                         format!("EOF")
                     };
-                    return Err(CheckError::new().msg_str(format!(
-                        "No closing ] in reference type with opening [! Found {nc} instead"
-                    )));
+                    return Err(CheckError::new()
+                        .src(vec![(
+                            (pos_in_src, src.get_pos(), srca).into(),
+                            Some(EColor::BracketedRefTypeNoClosingBracket),
+                        )])
+                        .msg_str(format!(
+                            "No closing ] in reference type with opening [! Found {nc} instead"
+                        )));
                 }
                 ParsedType::Reference(types)
             } else {
@@ -177,13 +183,28 @@ pub fn parse_single_type(src: &mut Source, srca: &Arc<Source>) -> Result<ParsedT
                 src.next_char();
                 ParsedType::TypeWithInfo(
                     t,
-                    super::statements::parse_string_custom_end(src, srca, pos, '<', '>')?,
+                    super::statements::parse_string_custom_end(
+                        src,
+                        srca,
+                        pos,
+                        '<',
+                        '>',
+                        "type-info ",
+                        EColor::TypeEOF,
+                    )?,
                 )
             } else {
                 ParsedType::Type(t)
             }
         }
-        None => todo!(),
+        None => {
+            return Err(CheckError::new()
+                .src(vec![(
+                    (src.get_pos_last_char(), src.get_pos(), srca).into(),
+                    Some(EColor::TypeEOF),
+                )])
+                .msg_str(format!("Expected type, got EOF")))
+        }
     })
 }
 
diff --git a/mers_lib/src/pretty_print.rs b/mers_lib/src/pretty_print.rs
new file mode 100644
index 0000000..1f678f8
--- /dev/null
+++ b/mers_lib/src/pretty_print.rs
@@ -0,0 +1,221 @@
+use std::{io::Write, process::exit, sync::Arc};
+
+use crate::{
+    prelude_compile::{parse, Source},
+    theme::ThemeGen,
+};
+
+#[cfg(not(feature = "ecolor-term"))]
+compile_error!("feature ecolor-term is required if pretty-print feature is enabled");
+
+pub fn pretty_print(src: Source) {
+    pretty_print_to(src, &mut std::io::stdout(), DefaultTheme)
+}
+
+pub fn pretty_print_to<O: Write>(mut src: Source, out: &mut O, theme: impl FTheme<O>) {
+    let srca = Arc::new(src.clone());
+    match parse(&mut src, &srca) {
+        Err(e) => {
+            eprintln!("{e:?}");
+            exit(28);
+        }
+        Ok(parsed) => {
+            print_parsed(&srca, parsed.as_ref(), out, theme);
+        }
+    }
+}
+
+pub enum AbstractColor {
+    Gray,
+    Green,
+    Red,
+    Blue,
+    Cyan,
+}
+pub fn map_color(color: FColor) -> Option<AbstractColor> {
+    Some(match color {
+        FColor::Comment => AbstractColor::Gray,
+        FColor::Variable => AbstractColor::Green,
+        FColor::VariableRef => AbstractColor::Green,
+        FColor::If => AbstractColor::Red,
+        FColor::IfWithElse => AbstractColor::Red,
+        FColor::Loop => AbstractColor::Red,
+        FColor::Tuple => AbstractColor::Blue,
+        FColor::Object => AbstractColor::Blue,
+        FColor::Value => AbstractColor::Cyan,
+        FColor::AsType => AbstractColor::Gray,
+        FColor::CustomType => AbstractColor::Gray,
+        FColor::Unknown => return None,
+    })
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub enum FColor {
+    Comment,
+    Variable,
+    VariableRef,
+    If,
+    IfWithElse,
+    Loop,
+    Tuple,
+    Object,
+    Value,
+    AsType,
+    CustomType,
+    Unknown,
+}
+
+pub struct DefaultTheme;
+impl ThemeGen for DefaultTheme {
+    type C = FColor;
+    type T = std::io::Stdout;
+    fn color(&self, text: &str, color: Self::C, t: &mut Self::T) {
+        use colored::{Color, Colorize};
+        if let Some(color) = map_color(color) {
+            let _ = write!(
+                t,
+                "{}",
+                text.color(match color {
+                    AbstractColor::Gray => Color::BrightBlack,
+                    AbstractColor::Green => Color::Green,
+                    AbstractColor::Red => Color::Red,
+                    AbstractColor::Blue => Color::Blue,
+                    AbstractColor::Cyan => Color::Cyan,
+                })
+            );
+        } else {
+            let _ = write!(t, "{}", text);
+        }
+    }
+    fn nocolor(&self, text: &str, t: &mut Self::T) {
+        let _ = write!(t, "{}", text);
+    }
+}
+
+// const FColor::Comment: Color = Color::BrightBlack;
+// const FColor::Variable: Color = Color::Green;
+// const FColor::Variable_Ref: Color = Color::Green;
+// const FColor::If: Color = Color::Red;
+// const FColor::If_With_Else: Color = Color::Red;
+// const FColor::Loop: Color = Color::Red;
+// const FColor::Tuple: Color = Color::Blue;
+// const FColor::Object: Color = Color::Blue;
+// const FColor::Value: Color = Color::Cyan;
+// const FColor::As_Type: Color = Color::BrightBlack;
+// const FColor::Custom_Type: Color = Color::BrightBlack;
+// const FColor::Unknown: Color = Color::White;
+
+pub trait FTheme<O>: ThemeGen<C = FColor, T = O> {}
+impl<O, T: ThemeGen<C = FColor, T = O>> FTheme<O> for T {}
+
+fn print_parsed<O: Write>(
+    srca: &Arc<Source>,
+    parsed: &dyn crate::program::parsed::MersStatement,
+    out: &mut O,
+    theme: impl FTheme<O>,
+) {
+    let mut sections = vec![(FColor::Unknown, srca.src_og().len())];
+    build_print(&mut sections, srca, parsed);
+    for (start, comment) in srca.comments() {
+        let end = start + comment.len();
+        build_print_insert_color(&mut sections, FColor::Comment, *start, end);
+    }
+    let src = srca.src_og();
+    let mut i = 0;
+    for (clr, end) in sections {
+        theme.color(&src[i..end], clr, out);
+        i = end;
+    }
+    let _ = writeln!(out);
+}
+fn build_print(
+    sections: &mut Vec<(FColor, usize)>,
+    srca: &Arc<Source>,
+    parsed: &dyn crate::program::parsed::MersStatement,
+) {
+    let any = parsed.as_any();
+    let clr = if let Some(v) = any.downcast_ref::<crate::program::parsed::variable::Variable>() {
+        if v.is_ref {
+            FColor::VariableRef
+        } else {
+            FColor::Variable
+        }
+    } else if let Some(v) = any.downcast_ref::<crate::program::parsed::r#if::If>() {
+        if v.on_false.is_some() {
+            FColor::IfWithElse
+        } else {
+            FColor::If
+        }
+    } else if let Some(_) = any.downcast_ref::<crate::program::parsed::r#loop::Loop>() {
+        FColor::Loop
+    } else if let Some(_) = any.downcast_ref::<crate::program::parsed::tuple::Tuple>() {
+        FColor::Tuple
+    } else if let Some(_) = any.downcast_ref::<crate::program::parsed::object::Object>() {
+        FColor::Object
+    } else if let Some(_) = any.downcast_ref::<crate::program::parsed::value::Value>() {
+        FColor::Value
+    } else if let Some(_) = any.downcast_ref::<crate::program::parsed::as_type::AsType>() {
+        FColor::AsType
+    } else if let Some(_) = any.downcast_ref::<crate::program::parsed::custom_type::CustomType>() {
+        FColor::CustomType
+    } else {
+        FColor::Unknown
+    };
+    let range = parsed.source_range();
+    let start = srca.pos_in_og(range.start().pos(), true);
+    let end = srca.pos_in_og(range.end().pos(), false);
+    build_print_insert_color(sections, clr, start, end);
+    for s in parsed.inner_statements() {
+        build_print(sections, srca, s);
+    }
+}
+
+fn build_print_insert_color(
+    sections: &mut Vec<(FColor, usize)>,
+    clr: FColor,
+    start: usize,
+    end: usize,
+) {
+    let thing_at_my_start = sections.iter().position(|v| v.1 > start);
+    let thing_at_my_end = sections.iter().position(|v| v.1 > end);
+    if let Some(thing_at_my_start) = thing_at_my_start {
+        if let Some(thing_at_my_end) = thing_at_my_end {
+            if thing_at_my_start == thing_at_my_end {
+                let (around_color, around_end) = sections[thing_at_my_start];
+                if around_color != clr {
+                    sections[thing_at_my_start].1 = start;
+                    sections.insert(thing_at_my_start + 1, (clr, end));
+                    sections.insert(thing_at_my_start + 2, (around_color, around_end));
+                    if sections[thing_at_my_start].1
+                        == thing_at_my_start
+                            .checked_sub(1)
+                            .map(|v| sections[v].1)
+                            .unwrap_or(0)
+                    {
+                        // thing at my start now ends at the same place the thing before it ends, so we can remove it
+                        sections.remove(thing_at_my_start);
+                    }
+                }
+            } else {
+                sections[thing_at_my_start].1 = start;
+                sections.insert(thing_at_my_start + 1, (clr, end));
+                for _ in 0..(thing_at_my_end.saturating_sub(thing_at_my_start + 1)) {
+                    sections.remove(thing_at_my_start + 2);
+                }
+            }
+        } else {
+            if sections[thing_at_my_start].0 == clr {
+                sections[thing_at_my_start].1 = end;
+            } else {
+                sections[thing_at_my_start].1 = start;
+                sections.push((clr, end));
+            }
+        }
+    } else {
+        if let Some(last) = sections.last_mut().filter(|v| v.0 == clr) {
+            last.1 = end;
+        } else {
+            sections.push((clr, end));
+        }
+    }
+}
diff --git a/mers_lib/src/program/run/chain.rs b/mers_lib/src/program/run/chain.rs
index 2edfe25..4591558 100755
--- a/mers_lib/src/program/run/chain.rs
+++ b/mers_lib/src/program/run/chain.rs
@@ -105,7 +105,12 @@ impl MersStatement for Chain {
                 }),
             }
         } else {
-            todo!("err: not a function");
+            Err(CheckError::new()
+                .msg_str("tried to chain with non-function".to_owned())
+                .src(vec![(
+                    self.chained.source_range(),
+                    Some(EColor::ChainWithNonFunction),
+                )]))
         }
     }
     fn has_scope(&self) -> bool {
diff --git a/mers_lib/src/theme.rs b/mers_lib/src/theme.rs
new file mode 100644
index 0000000..2d18aec
--- /dev/null
+++ b/mers_lib/src/theme.rs
@@ -0,0 +1,16 @@
+pub trait ThemeGen {
+    type C;
+    type T;
+    fn color(&self, text: &str, color: Self::C, t: &mut Self::T);
+    fn nocolor(&self, text: &str, t: &mut Self::T);
+}
+pub trait ThemeTo: ThemeGen<T = String> {
+    fn color_to(&self, text: &str, color: <Self as ThemeGen>::C) -> <Self as ThemeGen>::T;
+}
+impl<T: ThemeGen<T = String> + ?Sized> ThemeTo for T {
+    fn color_to(&self, text: &str, color: <T as ThemeGen>::C) -> String {
+        let mut t = String::new();
+        self.color(text, color, &mut t);
+        t
+    }
+}