diff --git a/compiler/cl-interpret/src/builtin.rs b/compiler/cl-interpret/src/builtin.rs
index 63249af..8d03883 100644
--- a/compiler/cl-interpret/src/builtin.rs
+++ b/compiler/cl-interpret/src/builtin.rs
@@ -178,6 +178,7 @@ pub const Builtins: &[Builtin] = &builtins![
     fn len(list) @env {
         Ok(match list {
             ConValue::Empty => 0,
+            ConValue::Str(s) => s.chars().count() as _,
             ConValue::String(s) => s.chars().count() as _,
             ConValue::Ref(r) => {
                 return len(env, &[env.get_id(*r).ok_or(Error::StackOverflow(*r))?.clone()])
@@ -203,6 +204,7 @@ pub const Builtins: &[Builtin] = &builtins![
 
     fn chars(string) @env {
         Ok(match string {
+            ConValue::Str(s) => ConValue::Array(s.chars().map(Into::into).collect()),
             ConValue::String(s) => ConValue::Array(s.chars().map(Into::into).collect()),
             ConValue::Ref(r) => {
                 return chars(env, &[env.get_id(*r).ok_or(Error::StackOverflow(*r))?.clone()])
@@ -259,7 +261,15 @@ pub const Math: &[Builtin] = &builtins![
         Ok(match (lhs, rhs) {
             (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
             (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a + b),
-            (ConValue::String(a), ConValue::String(b)) => (a.to_string() + &b.to_string()).into(),
+            (ConValue::Str(a), ConValue::Str(b)) => (a.to_string() + b).into(),
+            (ConValue::Str(a), ConValue::String(b)) => (a.to_string() + b).into(),
+            (ConValue::String(a), ConValue::Str(b)) => (a.to_string() + b).into(),
+            (ConValue::String(a), ConValue::String(b)) => (a.to_string() + b).into(),
+            (ConValue::Str(s), ConValue::Char(c)) => { let mut s = s.to_string(); s.push(*c); s.into() }
+            (ConValue::String(s), ConValue::Char(c)) => { let mut s = s.to_string(); s.push(*c); s.into() }
+            (ConValue::Char(a), ConValue::Char(b)) => {
+                ConValue::String([a, b].into_iter().collect::<String>())
+            }
             _ => Err(Error::TypeError())?
         })
     }
@@ -375,6 +385,9 @@ pub const Math: &[Builtin] = &builtins![
             (ConValue::Int(a), ConValue::Int(b)) => a.cmp(b) as _,
             (ConValue::Bool(a), ConValue::Bool(b)) => a.cmp(b) as _,
             (ConValue::Char(a), ConValue::Char(b)) => a.cmp(b) as _,
+            (ConValue::Str(a), ConValue::Str(b)) => a.cmp(b) as _,
+            (ConValue::Str(a), ConValue::String(b)) => a.to_ref().cmp(b.as_str()) as _,
+            (ConValue::String(a), ConValue::Str(b)) => a.as_str().cmp(b.to_ref()) as _,
             (ConValue::String(a), ConValue::String(b)) => a.cmp(b) as _,
             _ => Err(error_format!("Incomparable values: {head}, {tail}"))?
         }))
diff --git a/compiler/cl-interpret/src/convalue.rs b/compiler/cl-interpret/src/convalue.rs
index dfd685f..f65d82c 100644
--- a/compiler/cl-interpret/src/convalue.rs
+++ b/compiler/cl-interpret/src/convalue.rs
@@ -51,8 +51,10 @@ pub enum ConValue {
     Bool(bool),
     /// A unicode character
     Char(char),
-    /// A string
-    String(Sym),
+    /// A string literal
+    Str(Sym),
+    /// A dynamic string
+    String(String),
     /// A reference
     Ref(usize),
     /// A reference to an array
@@ -97,6 +99,7 @@ impl ConValue {
             ConValue::Float(_) => "f64",
             ConValue::Bool(_) => "bool",
             ConValue::Char(_) => "char",
+            ConValue::Str(_) => "str",
             ConValue::String(_) => "String",
             ConValue::Ref(_) => "Ref",
             ConValue::Slice(_, _) => "Slice",
@@ -128,6 +131,11 @@ impl ConValue {
             Err(Error::TypeError())?
         };
         match self {
+            ConValue::Str(string) => string
+                .chars()
+                .nth(index as _)
+                .map(ConValue::Char)
+                .ok_or(Error::OobIndex(index as usize, string.chars().count())),
             ConValue::String(string) => string
                 .chars()
                 .nth(index as _)
@@ -216,6 +224,9 @@ macro cmp ($($fn:ident: $empty:literal, $op:tt);*$(;)?) {$(
             (Self::Float(a), Self::Float(b)) => Ok(Self::Bool(a $op b)),
             (Self::Bool(a), Self::Bool(b)) => Ok(Self::Bool(a $op b)),
             (Self::Char(a), Self::Char(b)) => Ok(Self::Bool(a $op b)),
+            (Self::Str(a), Self::Str(b)) => Ok(Self::Bool(&**a $op &**b)),
+            (Self::Str(a), Self::String(b)) => Ok(Self::Bool(&**a $op &**b)),
+            (Self::String(a), Self::Str(b)) => Ok(Self::Bool(&**a $op &**b)),
             (Self::String(a), Self::String(b)) => Ok(Self::Bool(&**a $op &**b)),
             _ => Err(Error::TypeError())
         }
@@ -235,7 +246,7 @@ macro from ($($T:ty => $v:expr),*$(,)?) {
 }
 impl From<&Sym> for ConValue {
     fn from(value: &Sym) -> Self {
-        ConValue::String(*value)
+        ConValue::Str(*value)
     }
 }
 from! {
@@ -243,11 +254,11 @@ from! {
     f64 => ConValue::Float,
     bool => ConValue::Bool,
     char => ConValue::Char,
-    Sym => ConValue::String,
-    &str => ConValue::String,
+    Sym => ConValue::Str,
+    &str => ConValue::Str,
     Expr => ConValue::Quote,
     String => ConValue::String,
-    Rc<str> => ConValue::String,
+    Rc<str> => ConValue::Str,
     Function => ConValue::Function,
     Vec<ConValue> => ConValue::Tuple,
     &'static Builtin => ConValue::Builtin,
@@ -282,10 +293,14 @@ ops! {
         (ConValue::Empty, ConValue::Empty) => ConValue::Empty,
         (ConValue::Int(a), ConValue::Int(b)) => ConValue::Int(a.wrapping_add(b)),
         (ConValue::Float(a), ConValue::Float(b)) => ConValue::Float(a + b),
+        (ConValue::Str(a), ConValue::Str(b)) => (a.to_string() + &*b).into(),
+        (ConValue::Str(a), ConValue::String(b)) => (a.to_string() + &*b).into(),
+        (ConValue::String(a), ConValue::Str(b)) => (a.to_string() + &*b).into(),
         (ConValue::String(a), ConValue::String(b)) => (a.to_string() + &*b).into(),
+        (ConValue::Str(s), ConValue::Char(c)) => { let mut s = s.to_string(); s.push(c); s.into() }
         (ConValue::String(s), ConValue::Char(c)) => { let mut s = s.to_string(); s.push(c); s.into() }
         (ConValue::Char(a), ConValue::Char(b)) => {
-            ConValue::String([a, b].into_iter().collect::<String>().into())
+            ConValue::String([a, b].into_iter().collect::<String>())
         }
         _ => Err(Error::TypeError())?
         ]
@@ -354,6 +369,7 @@ impl std::fmt::Display for ConValue {
             ConValue::Float(v) => v.fmt(f),
             ConValue::Bool(v) => v.fmt(f),
             ConValue::Char(v) => v.fmt(f),
+            ConValue::Str(v) => v.fmt(f),
             ConValue::String(v) => v.fmt(f),
             ConValue::Ref(v) => write!(f, "&<{}>", v),
             ConValue::Slice(id, len) => write!(f, "&<{id}>[{len}..]"),
diff --git a/compiler/cl-interpret/src/interpret.rs b/compiler/cl-interpret/src/interpret.rs
index af3168b..9003dc7 100644
--- a/compiler/cl-interpret/src/interpret.rs
+++ b/compiler/cl-interpret/src/interpret.rs
@@ -699,7 +699,7 @@ fn cast(env: &Environment, value: ConValue, ty: Sym) -> IResult<ConValue> {
         // TODO: This, better
         ConValue::Float(_) if ty.starts_with('f') => return Ok(value),
         ConValue::Float(f) => f as _,
-        _ if (*ty).eq("str") => return Ok(ConValue::String(format!("{value}").into())),
+        _ if (*ty).eq("str") => return Ok(ConValue::Str(format!("{value}").into())),
         _ => Err(Error::TypeError())?,
     };
     Ok(match &*ty {
@@ -958,7 +958,7 @@ impl Interpret for For {
             &ConValue::Slice(head, len) => Box::new((head..head + len).map(ConValue::Ref)),
             // In the production compiler this may be fully unrolled
             ConValue::Tuple(t) => Box::new(t.iter().cloned()),
-            ConValue::String(s) => Box::new(s.chars().map(ConValue::Char)),
+            ConValue::Str(s) => Box::new(s.chars().map(ConValue::Char)),
             _ => Err(Error::TypeError())?,
         };
         loop {
diff --git a/compiler/cl-interpret/src/pattern.rs b/compiler/cl-interpret/src/pattern.rs
index 907399a..34a1f90 100644
--- a/compiler/cl-interpret/src/pattern.rs
+++ b/compiler/cl-interpret/src/pattern.rs
@@ -139,6 +139,9 @@ pub fn append_sub(
         (Pattern::Literal(Literal::Int(a)), ConValue::Int(b)) => {
             (b == *a as _).then_some(()).ok_or(Error::NotAssignable())
         }
+        (Pattern::Literal(Literal::String(a)), ConValue::Str(b)) => {
+            (*a == *b).then_some(()).ok_or(Error::NotAssignable())
+        }
         (Pattern::Literal(Literal::String(a)), ConValue::String(b)) => {
             (*a == *b).then_some(()).ok_or(Error::NotAssignable())
         }
@@ -157,6 +160,9 @@ pub fn append_sub(
             (Pattern::Literal(Literal::Float(a)), ConValue::Float(b)) => {
                 (b < *a as _).then_some(()).ok_or(Error::NotAssignable())
             }
+            (Pattern::Literal(Literal::String(a)), ConValue::Str(b)) => {
+                (&*b < a).then_some(()).ok_or(Error::NotAssignable())
+            }
             (Pattern::Literal(Literal::String(a)), ConValue::String(b)) => {
                 (&*b < a).then_some(()).ok_or(Error::NotAssignable())
             }
@@ -207,10 +213,17 @@ pub fn append_sub(
             (
                 Pattern::Literal(Literal::String(a)),
                 Pattern::Literal(Literal::String(c)),
-                ConValue::String(b),
+                ConValue::Str(b),
             ) => (a.as_str() <= b.to_ref() && b.to_ref() < c.as_str())
                 .then_some(())
                 .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::String(a)),
+                Pattern::Literal(Literal::String(c)),
+                ConValue::String(b),
+            ) => (a.as_str() <= b.as_str() && b.as_str() < c.as_str())
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
             _ => Err(Error::NotAssignable()),
         },
 
@@ -239,10 +252,17 @@ pub fn append_sub(
             (
                 Pattern::Literal(Literal::String(a)),
                 Pattern::Literal(Literal::String(c)),
-                ConValue::String(b),
+                ConValue::Str(b),
             ) => (a.as_str() <= b.to_ref() && b.to_ref() <= c.as_str())
                 .then_some(())
                 .ok_or(Error::NotAssignable()),
+            (
+                Pattern::Literal(Literal::String(a)),
+                Pattern::Literal(Literal::String(c)),
+                ConValue::String(b),
+            ) => (a.as_str() <= b.as_str() && b.as_str() <= c.as_str())
+                .then_some(())
+                .ok_or(Error::NotAssignable()),
             _ => Err(Error::NotAssignable()),
         },
 
diff --git a/compiler/cl-repl/src/cli.rs b/compiler/cl-repl/src/cli.rs
index de2490d..36a8eb1 100644
--- a/compiler/cl-repl/src/cli.rs
+++ b/compiler/cl-repl/src/cli.rs
@@ -26,23 +26,29 @@ pub fn run(args: Args) -> Result<(), Box<dyn Error>> {
 
         fn eval(string) @env {
             use cl_interpret::error::Error;
-            let string = match *string {
-                ConValue::String(string) => string,
+            let string = match string {
+                ConValue::Str(string) => string.to_ref(),
+                ConValue::String(string) => string.as_str(),
                 ConValue::Ref(v) => {
-                    let string = env.get_id(v).cloned().unwrap_or_default();
+                    let string = env.get_id(*v).cloned().unwrap_or_default();
                     return eval(env, &[string])
                 }
                 _ => Err(Error::TypeError())?
             };
-            match Parser::new("eval", Lexer::new(string.to_ref())).parse::<cl_ast::Stmt>() {
-                Err(e) => Ok(ConValue::String(format!("{e}").into())),
+            match Parser::new("eval", Lexer::new(string)).parse::<cl_ast::Stmt>() {
+                Err(e) => Ok(ConValue::Str(format!("{e}").into())),
                 Ok(v) => v.interpret(env),
             }
         }
 
         /// Executes a file
-        fn import(ConValue::String(path)) @env {
-            load_file(env, &**path).or(Ok(ConValue::Empty))
+        fn import(path) @env {
+            use cl_interpret::error::Error;
+            match path {
+                ConValue::Str(path) => load_file(env, &**path).or(Ok(ConValue::Empty)),
+                ConValue::String(path) => load_file(env, &**path).or(Ok(ConValue::Empty)),
+                _ => Err(Error::TypeError())
+            }
         }
 
         fn putchar(ConValue::Char(c)) {
@@ -51,12 +57,18 @@ pub fn run(args: Args) -> Result<(), Box<dyn Error>> {
         }
 
         /// Gets a line of input from stdin
-        fn get_line(ConValue::String(prompt)) {
-            match repline::Repline::new("", prompt.to_ref(), "").read() {
-                Ok(line) => Ok(ConValue::String(line.into())),
-                Err(repline::Error::CtrlD(line)) => Ok(ConValue::String(line.into())),
+        fn get_line(prompt) {
+            use cl_interpret::error::Error;
+            let prompt = match prompt {
+                ConValue::Str(prompt) => prompt.to_ref(),
+                ConValue::String(prompt) => prompt.as_str(),
+                _ => Err(Error::TypeError())?,
+            };
+            match repline::Repline::new("", prompt, "").read() {
+                Ok(line) => Ok(ConValue::String(line)),
+                Err(repline::Error::CtrlD(line)) => Ok(ConValue::String(line)),
                 Err(repline::Error::CtrlC(_)) => Err(cl_interpret::error::Error::Break(ConValue::Empty)),
-                Err(e) => Ok(ConValue::String(e.to_string().into())),
+                Err(e) => Ok(ConValue::Str(e.to_string().into())),
             }
         }
     });
diff --git a/sample-code/fstring.cl b/sample-code/fstring.cl
index c3d91f3..f820b8b 100644
--- a/sample-code/fstring.cl
+++ b/sample-code/fstring.cl
@@ -2,6 +2,7 @@
 fn f(__fmt: str) -> str {
     let __out = "";
     let __expr = "";
+    let __label = "";
     let __depth = 0;
     for __c in chars(__fmt) {
         match __c {
@@ -14,19 +15,26 @@ fn f(__fmt: str) -> str {
             '}' => {
                 __depth -= 1
                 if __depth <= 0 {
-                    __out += fmt(eval(__expr))
-                    __expr = ""
+                    __out = fmt(__out, __label, eval(__expr));
+                    (__expr, __label) = ("", "");
                     continue
                 }
             },
-            ':' => if __depth == 1 {
-                __out += __expr + ": "
+            ':' => if __depth == 1 && __label.len() == 0 {
+                __label = __expr + __c
+                continue
+            },
+            '=' => if __depth == 1 && __label.len() == 0 {
+                __label = __expr + __c
+                continue
             },
             _ => {}
         }
-        if __depth > 0 {
-            __expr += __c
-        } else __out += __c;
+        match (__depth, __label.len()) {
+            (0, _) => __out += __c,
+            (_, 0) => __expr += __c,
+            (_, _) => __label += __c,
+        }
     }
     __out
 }