refactor: rename modules to nicer names

this doesn't always work still;
there are a lot of panicking index operations there.

a feature was stabilized very recently that would help fix that:
https://github.com/rust-lang/rust/issues/146954

Cargo.toml

@@ -10,3 +10,7 @@ thiserror = "2.0.18"
 version = "1.30"
 default-features = false
 features = ["std", "float"]
+
+[profile.release]
+lto = true
+codegen-units = 1

flake.nix

@@ -12,14 +12,14 @@
       let
         pkgs = import inputs.nixpkgs { inherit system; };
 
-        cargoToml = fromTOML (builtins.readFile ./Cargo.toml);
+        src = ./.;
+        cargoToml = fromTOML (builtins.readFile "${src}/Cargo.toml");
         name = cargoToml.package.name;
 
         crate = pkgs.rustPlatform.buildRustPackage {
-          inherit name;
-          src = ./.;
+          inherit name src;
 
-          cargoLock.lockFile = ./Cargo.lock;
+          cargoLock.lockFile = "${src}/Cargo.lock";
 
           nativeBuildInputs = with pkgs; [
             m4

src/formatting.rs

@@ -0,0 +1,100 @@
+use std::str::FromStr;
+
+use rug::Float;
+
+use crate::nodes::{Error, Nodes};
+
+pub fn pretty_eval(mut input: String) -> Result<String, Error> {
+    // no need to remove the characters here,
+    // as we ignore the them in all other logic already
+    let should_add_back_alignment = input.contains('&');
+    let should_add_back_backslash = input.contains('\\');
+    let leading_spaces = input.chars().take_while(|c| *c == ' ').count();
+
+    let should_add_back_equals = input
+        .find('=')
+        .inspect(|i| {
+            input.remove(*i);
+        })
+        .is_some();
+
+    let result = Nodes::from_str(&input)?.evaluate()?;
+    let significant_digits = get_significant_digits(&result);
+
+    Ok(format!(
+        "{:leading_spaces$}{}{result:.significant_digits$}{}",
+        ' ',
+        if should_add_back_equals && should_add_back_alignment {
+            "& = "
+        } else if should_add_back_equals {
+            "= "
+        } else if should_add_back_alignment {
+            "& "
+        } else {
+            ""
+        },
+        if should_add_back_backslash { " \\" } else { "" }
+    ))
+}
+#[test]
+fn test_character_readdition() {
+    assert_eq!(pretty_eval(" = 11".into()).unwrap(), " = 11");
+    assert_eq!(pretty_eval(" &= 11".into()).unwrap(), " & = 11");
+    assert_eq!(pretty_eval(" & 11".into()).unwrap(), " & 11");
+    assert_eq!(pretty_eval(" & 11 \\".into()).unwrap(), " & 11 \\");
+}
+
+pub fn get_significant_digits(n: &Float) -> usize {
+    let raw_string: String = format!("{n}").chars().filter(|c| *c != '.').collect();
+
+    let mut consecutive_zeros = 0;
+    let mut consecutive_nines = 0;
+    for (i, c) in raw_string.char_indices() {
+        if c == '0' {
+            consecutive_zeros += 1;
+        } else {
+            consecutive_zeros = 0;
+        }
+
+        if c == '9' {
+            consecutive_nines += 1;
+        } else {
+            consecutive_nines = 0;
+        }
+
+        if consecutive_zeros >= 10 {
+            return i + 1 - consecutive_zeros;
+        } else if consecutive_nines >= 10 {
+            return i + 1 - consecutive_nines;
+        }
+
+        if !raw_string[i..raw_string.len()].contains(|c| matches!(c, '1'..='9')) {
+            return i;
+        }
+    }
+
+    // all digits are significant
+    raw_string.len()
+}
+
+#[cfg(test)]
+fn eval(s: &str) -> Float {
+    crate::nodes::eval(s).unwrap()
+}
+
+#[test]
+fn test_get_significant_digits() {
+    let many_zeros = eval("14.00643 + 1.00784 * 4 + 35.446 + 15.9994 * 4");
+    assert_eq!(many_zeros.to_f64(), 117.48139);
+    let many_nines = eval("12.0096 + 15.9994 * 2");
+    assert_eq!(many_nines.to_f64(), 44.0084);
+    let zero_nine_zero = eval("2+12321(5+123)");
+    assert_eq!(zero_nine_zero.to_f64(), 1577090.0);
+    let test_4 = eval("12.0096 + 1.00784 * 3 + 12.0096 + 1.00784 * 2 + 15.9994 + 1.00784");
+    assert_eq!(test_4.to_f64(), 46.06564);
+
+    assert_eq!(get_significant_digits(&many_zeros), 8);
+    assert_eq!(get_significant_digits(&many_nines), 6);
+    assert_eq!(get_significant_digits(&zero_nine_zero), 6);
+    assert_eq!(get_significant_digits(&test_4), 7);
+}

src/lib.rs

@@ -0,0 +1,4 @@
+pub mod formatting;
+pub mod nodes;
+
+pub use nodes::eval;

src/main.rs

@@ -1,14 +1,13 @@
 use std::{
     env,
     io::{self, Read},
-    str::FromStr,
+    process::ExitCode,
 };
 
-use rug::Float;
-
+mod formatting;
 mod nodes;
 
-fn main() {
+fn main() -> ExitCode {
     let input = match env::args().skip(1).rev().reduce(|x, a| a + &x) {
         Some(s) => s,
         None => {
@@ -18,100 +17,14 @@ fn main() {
         }
     };
 
-    println!("{}", parse_and_calc_humanreadable(input));
-}
+    match formatting::pretty_eval(input) {
+        Ok(s) => println!("{s}"),
 
-pub fn parse_and_calc_humanreadable(mut input: String) -> String {
-    let should_add_back_equals = if let Some((i, _)) = input
-        .chars()
-        .enumerate()
-        .filter(|(_, c)| !matches!(c, ' ' | '&' | '\n'))
-        .find(|(_, c)| *c == '=')
-    {
-        input.remove(i);
-        true
-    } else {
-        false
-    };
-
-    // no need to remove the character here,
-    // as we ignore the ampersand in all other logic already
-    let should_add_back_alignment = input.contains('&');
-
-    let result = parse_and_calc(&input);
-
-    format!(
-        "{0}{result:.1$}",
-        if should_add_back_equals && should_add_back_alignment {
-            "& = "
-        } else if should_add_back_equals {
-            "= "
-        } else if should_add_back_alignment {
-            "& "
-        } else {
-            ""
-        },
-        get_significant_digits(&result),
-    )
-}
-#[test]
-fn test_equals_readdition() {
-    assert_eq!(parse_and_calc_humanreadable(" = 11".into()), "= 11");
-    assert_eq!(parse_and_calc_humanreadable(" &= 11".into()), "& = 11");
-    assert_eq!(parse_and_calc_humanreadable(" & 11".into()), "& 11");
-}
-
-pub fn parse_and_calc(s: &str) -> Float {
-    nodes::Nodes::from_str(s).unwrap().evaluate()
-}
-
-pub fn get_significant_digits(n: &Float) -> usize {
-    let raw_string: String = format!("{n}").chars().filter(|c| *c != '.').collect();
-
-    let mut consecutive_zeros = 0;
-    let mut consecutive_nines = 0;
-    for (i, c) in raw_string.char_indices() {
-        if c == '0' {
-            consecutive_zeros += 1;
-        } else {
-            consecutive_zeros = 0;
-        }
-
-        if c == '9' {
-            consecutive_nines += 1;
-        } else {
-            consecutive_nines = 0;
-        }
-
-        if consecutive_zeros >= 10 {
-            return i + 1 - consecutive_zeros;
-        } else if consecutive_nines >= 10 {
-            return i + 1 - consecutive_nines;
-        }
-
-        if !raw_string[i..raw_string.len()].contains(|c| matches!(c, '1'..='9')) {
-            return i;
+        Err(e) => {
+            eprintln!("{e}");
+            return ExitCode::FAILURE;
         }
     }
 
-    // all digits are significant
-    raw_string.len()
-}
-
-#[test]
-fn test_get_significant_digits() {
-    let many_zeros = parse_and_calc("14.00643 + 1.00784 * 4 + 35.446 + 15.9994 * 4");
-    assert_eq!(many_zeros.to_f64(), 117.48139);
-    let many_nines = parse_and_calc("12.0096 + 15.9994 * 2");
-    assert_eq!(many_nines.to_f64(), 44.0084);
-    let zero_nine_zero = parse_and_calc("2+12321(5+123)");
-    assert_eq!(zero_nine_zero.to_f64(), 1577090.0);
-    let test_4 =
-        parse_and_calc("12.0096 + 1.00784 * 3 + 12.0096 + 1.00784 * 2 + 15.9994 + 1.00784");
-    assert_eq!(test_4.to_f64(), 46.06564);
-
-    assert_eq!(get_significant_digits(&many_zeros), 8);
-    assert_eq!(get_significant_digits(&many_nines), 6);
-    assert_eq!(get_significant_digits(&zero_nine_zero), 6);
-    assert_eq!(get_significant_digits(&test_4), 7);
+    ExitCode::SUCCESS
 }

src/nodes/eval.rs

@@ -0,0 +1,188 @@
+use rug::{
+    Float,
+    ops::{AddFrom, DivFrom, MulFrom, PowFrom, SubFrom},
+};
+
+use crate::nodes::{Function, Node, Nodes, Operator};
+
+#[derive(Clone, Debug, thiserror::Error)]
+pub enum Error {
+    #[error("invalid operand: {0}")]
+    InvalidOperand(Node),
+    #[error("missing argument, got: {0}")]
+    MissingArgument(Node),
+    #[error("collapse failed, left with: {0}")]
+    CollapseFailed(Nodes),
+}
+
+impl Nodes {
+    /// Consume the `Nodes`, collapsing them down to a single number
+    pub fn evaluate(mut self) -> Result<Float, Error> {
+        let nodes = &mut self.0;
+
+        while let Some(end) = nodes.iter().position(|n| *n == Node::ParenthesisEnd) {
+            collapse_toplevel(nodes, end)?;
+        }
+        let len = nodes.len();
+        collapse_toplevel(nodes, len)?;
+
+        match nodes.pop().unwrap() {
+            Node::Number(n) => Ok(n),
+            _ => Err(Error::CollapseFailed(self)),
+        }
+    }
+}
+
+fn collapse_toplevel(nodes: &mut Vec<Node>, mut end: usize) -> Result<(), Error> {
+    let start = nodes[0..end]
+        .iter()
+        .rposition(|n| *n == Node::ParenthesisStart)
+        .unwrap_or(0);
+
+    while let Some((index, variant)) = nodes[start..end]
+        .iter()
+        .enumerate()
+        .filter_map(|(i, n)| match n {
+            Node::Function(f) => Some((i, *f)),
+            _ => None,
+        })
+        .next()
+    {
+        match &mut nodes[start..end][index + 1] {
+            Node::Number(n) => match variant {
+                Function::Sqrt => n.sqrt_mut(),
+
+                Function::Sine => n.sin_mut(),
+                Function::ArcSine => n.asin_mut(),
+                Function::Cosine => n.cos_mut(),
+                Function::ArcCosine => n.acos_mut(),
+                Function::Tangent => n.tan_mut(),
+                Function::ArcTangent => n.atan_mut(),
+                Function::Secant => n.sec_mut(),
+                Function::CoSecant => n.csc_mut(),
+            },
+            n => return Err(Error::MissingArgument(n.clone())),
+        };
+
+        nodes.remove(start + index);
+        end -= 1;
+    }
+
+    while let Some(operator) = nodes[start..end]
+        .iter()
+        .position(|n| *n == Node::Operator(Operator::Exp))
+    {
+        let lhs = match nodes.remove(start + operator - 1) {
+            Node::Number(n) => n,
+            n => return Err(Error::InvalidOperand(n)),
+        };
+        end -= 1;
+        match &mut nodes[start..end][operator] {
+            Node::Number(n) => n.pow_from(lhs),
+            n => return Err(Error::InvalidOperand(n.clone())),
+        };
+
+        nodes.remove(start + operator - 1);
+        end -= 1;
+    }
+
+    while let Some(operator) = nodes[start..end]
+        .iter()
+        .position(|n| *n == Node::Operator(Operator::Div))
+    {
+        let lhs = match nodes.remove(start + operator - 1) {
+            Node::Number(n) => n,
+            n => return Err(Error::InvalidOperand(n)),
+        };
+        end -= 1;
+        match &mut nodes[start..end][operator] {
+            Node::Number(n) => n.div_from(lhs),
+            n => return Err(Error::InvalidOperand(n.clone())),
+        };
+
+        nodes.remove(start + operator - 1);
+        end -= 1;
+    }
+
+    while let Some(operator) = nodes[start..end]
+        .iter()
+        .position(|n| *n == Node::Operator(Operator::Mult))
+    {
+        let lhs = match nodes.remove(start + operator - 1) {
+            Node::Number(n) => n,
+            n => return Err(Error::InvalidOperand(n)),
+        };
+        end -= 1;
+        match &mut nodes[start..end][operator] {
+            Node::Number(n) => n.mul_from(lhs),
+            n => return Err(Error::InvalidOperand(n.clone())),
+        };
+
+        nodes.remove(start + operator - 1);
+        end -= 1;
+    }
+
+    while let Some(operator) = nodes[start..end]
+        .iter()
+        .position(|n| *n == Node::Operator(Operator::Minus))
+    {
+        let lhs = match nodes.remove(start + operator - 1) {
+            Node::Number(n) => n,
+            n => return Err(Error::InvalidOperand(n)),
+        };
+        end -= 1;
+        match &mut nodes[start..end][operator] {
+            Node::Number(n) => n.sub_from(lhs),
+            n => return Err(Error::InvalidOperand(n.clone())),
+        };
+
+        nodes.remove(start + operator - 1);
+        end -= 1;
+    }
+
+    while let Some(operator) = nodes[start..end]
+        .iter()
+        .position(|n| *n == Node::Operator(Operator::Plus))
+    {
+        let lhs = match nodes.remove(start + operator - 1) {
+            Node::Number(n) => n,
+            n => return Err(Error::InvalidOperand(n)),
+        };
+        end -= 1;
+        match &mut nodes[start..end][operator] {
+            Node::Number(n) => n.add_from(lhs),
+            n => return Err(Error::InvalidOperand(n.clone())),
+        };
+
+        nodes.remove(start + operator - 1);
+        end -= 1;
+    }
+
+    if nodes.len() > 1 {
+        nodes.remove(end);
+        nodes.remove(start);
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+use super::PREC;
+
+#[test]
+fn test() {
+    assert_eq!(
+        Nodes(vec![
+            Node::Function(Function::Sine),
+            Node::ParenthesisStart,
+            Node::Number(Float::with_val(PREC, 2)),
+            Node::ParenthesisEnd,
+            Node::Operator(Operator::Plus),
+            Node::Number(Float::with_val(PREC, 1))
+        ])
+        .evaluate()
+        .unwrap()
+        .to_f64(),
+        1.9092974268256817,
+    );
+}

src/nodes/mod.rs

@@ -2,13 +2,29 @@
 //! as well as the logic to parse it from a string (`Node::from_str`),
 //! and the logic to evaluate it into a single number (`Node::evaluate`).
 
+use std::fmt::{Debug, Display};
+
 use rug::Float;
 
-mod evaluate;
-mod from_str;
+mod eval;
+pub mod parse;
 #[cfg(test)]
 mod tests;
 
+#[derive(Clone, Debug, thiserror::Error)]
+pub enum Error {
+    #[error("{0}")]
+    Parsing(#[from] parse::Error),
+    #[error("{0}")]
+    Evaluation(#[from] eval::Error),
+}
+
+/// helper function to parse to Nodes and immediately evaluate
+pub fn eval(s: &str) -> Result<rug::Float, Error> {
+    use std::str::FromStr;
+    Ok(Nodes::from_str(s)?.evaluate()?)
+}
+
 pub const PREC: u32 = 512;
 
 #[derive(Debug, Default, Clone, PartialEq)]
@@ -18,18 +34,28 @@ impl AsRef<[Node]> for Nodes {
         self.0.as_ref()
     }
 }
+impl Display for Nodes {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        Debug::fmt(&self.0, f)
+    }
+}
 
 #[derive(Debug, Clone, PartialEq)]
-enum Node {
+pub enum Node {
     Function(Function),
     ParenthesisStart,
     ParenthesisEnd,
     Number(Float),
     Operator(Operator),
 }
+impl Display for Node {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        Debug::fmt(&self, f)
+    }
+}
 
 #[derive(Debug, Default, Copy, Clone, PartialEq)]
-enum Operator {
+pub enum Operator {
     Plus,
     Minus,
     #[default]
@@ -39,7 +65,7 @@ enum Operator {
 }
 
 #[derive(Debug, Copy, Clone, PartialEq)]
-enum Function {
+pub enum Function {
     Sqrt,
 
     Sine,

src/nodes/parse.rs

@@ -0,0 +1,205 @@
+use core::f64;
+use std::str::FromStr;
+
+use rug::{Float, float::ParseFloatError, ops::CompleteRound};
+
+use crate::nodes::{Function, Node, Nodes, Operator, PREC};
+
+impl Node {
+    fn from_name(s: &str) -> Result<Self, String> {
+        Ok(match s {
+            "c" => Self::Number(Float::with_val(PREC, 299_792_458)),
+            "A" => Self::Number(Float::with_val(PREC, 6.02214076e23)),
+            "pi" => Self::Number(Float::with_val(PREC, f64::consts::PI)),
+            // Planck's constant, in J*s (joule-seconds)
+            "h" => Self::Number(Float::with_val(PREC, 6.62607015e-34)),
+            _ => Self::Function(s.parse()?),
+        })
+    }
+}
+impl TryFrom<char> for Operator {
+    type Error = char;
+    fn try_from(value: char) -> Result<Self, Self::Error> {
+        match value {
+            '+' => Ok(Self::Plus),
+            '-' | '−' => Ok(Self::Minus),
+            '*' | '×' => Ok(Self::Mult),
+            '/' | '÷' => Ok(Self::Div),
+            '^' => Ok(Self::Exp),
+            _ => Err(value),
+        }
+    }
+}
+impl FromStr for Function {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "sqrt" => Ok(Self::Sqrt),
+
+            "sin" => Ok(Self::Sine),
+            "asin" => Ok(Self::ArcSine),
+            "cos" => Ok(Self::Cosine),
+            "acos" => Ok(Self::ArcCosine),
+            "tan" => Ok(Self::Tangent),
+            "atan" => Ok(Self::ArcTangent),
+            "sec" => Ok(Self::Secant),
+            "csc" => Ok(Self::CoSecant),
+            _ => Err(s.to_owned()),
+        }
+    }
+}
+
+#[derive(Clone, Debug, thiserror::Error)]
+pub enum Error {
+    #[error("unrecognized function/constant: {0}")]
+    UnrecognizedName(String),
+    #[error("invalid operator: {0}")]
+    InvalidOperator(char),
+    #[error("failed to parse number '{0}': {1}")]
+    NumberParsing(String, ParseFloatError),
+}
+#[derive(Clone, Debug, Default, PartialEq)]
+enum ParsingState {
+    #[default]
+    Start,
+    ReadingFunctionName(usize),
+    ReadingNumber(usize),
+}
+impl FromStr for Nodes {
+    type Err = Error;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        /// A superset of `char::is_numeric`
+        /// that includes other characters parseable into numbers,
+        /// such as `.` (for decimal) and `e` for scientific notation.
+        fn is_number_char(c: char) -> bool {
+            match c {
+                '.' | 'e' => true,
+                c => c.is_numeric(),
+            }
+        }
+        /// A function to check if the given `char` should be used by the parser.
+        ///
+        /// We ignore whitespace since it has no semantic significance in typst
+        /// (aside from variables, which are not implemented)
+        /// and `&`, `\` because they are only used for visual alignment.
+        ///
+        /// Newlines are also ignored because they're likely accidental;
+        /// like in the case of `echo 1+1 | tylc`.
+        fn is_not_ignored_char(c: &char) -> bool {
+            !matches!(c, ' ' | '&' | '\n' | '\\')
+        }
+
+        let mut nodes = Vec::new();
+        let mut state = ParsingState::default();
+
+        let filtered_string: String = s.chars().filter(is_not_ignored_char).collect();
+
+        for (i, c) in filtered_string.char_indices() {
+            // check whether we're at the end of the bit we're parsing
+            match state {
+                ParsingState::Start => {}
+                ParsingState::ReadingFunctionName(start_index) => {
+                    if !c.is_alphabetic() {
+                        if matches!(nodes.last(), Some(Node::ParenthesisEnd | Node::Number(_))) {
+                            nodes.push(Node::Operator(Default::default()));
+                        }
+
+                        nodes.push(
+                            Node::from_name(&filtered_string[start_index..i])
+                                .map_err(Error::UnrecognizedName)?,
+                        );
+
+                        state = ParsingState::Start;
+                    }
+                }
+                ParsingState::ReadingNumber(start_index) => {
+                    if !is_number_char(c)
+                        // don't stop reading number on a special case, eg "1e-1"
+                        && !(filtered_string.chars().nth(i - 1) == Some('e') && c == '-')
+                    {
+                        nodes.push(Node::Number(
+                            Float::parse(&filtered_string[start_index..i])
+                                .map_err(|e| {
+                                    Error::NumberParsing(
+                                        filtered_string[start_index..i].to_owned(),
+                                        e,
+                                    )
+                                })?
+                                .complete(PREC),
+                        ));
+
+                        state = ParsingState::Start;
+                    }
+                }
+            }
+
+            // start parsing something new (if applicable)
+            if state == ParsingState::Start {
+                if is_number_char(c) {
+                    state = ParsingState::ReadingNumber(i);
+                } else if c.is_alphabetic() {
+                    state = ParsingState::ReadingFunctionName(i);
+                } else if c == '(' {
+                    if matches!(nodes.last(), Some(Node::Number(_) | Node::ParenthesisEnd)) {
+                        nodes.push(Node::Operator(Default::default()));
+                    }
+                    nodes.push(Node::ParenthesisStart);
+                } else if c == ')' {
+                    nodes.push(Node::ParenthesisEnd);
+                } else {
+                    if matches!(nodes.last(), Some(Node::Operator(_)) | None) {
+                        state = ParsingState::ReadingNumber(i);
+                    } else {
+                        nodes.push(Node::Operator(
+                            c.try_into().map_err(Error::InvalidOperator)?,
+                        ));
+                    }
+                }
+            }
+        }
+
+        // wrap up any unfinished parsing
+        let i = filtered_string.len();
+        match state {
+            ParsingState::Start => {}
+            ParsingState::ReadingFunctionName(start_index) => {
+                if matches!(nodes.last(), Some(Node::ParenthesisEnd | Node::Number(_))) {
+                    nodes.push(Node::Operator(Default::default()));
+                }
+                nodes.push(
+                    Node::from_name(&filtered_string[start_index..i])
+                        .map_err(Error::UnrecognizedName)?,
+                );
+            }
+            ParsingState::ReadingNumber(start_index) => {
+                if matches!(nodes.last(), Some(Node::ParenthesisEnd)) {
+                    nodes.push(Node::Operator(Default::default()));
+                }
+                nodes.push(Node::Number(
+                    Float::parse(&filtered_string[start_index..i])
+                        .map_err(|e| {
+                            Error::NumberParsing(filtered_string[start_index..i].to_owned(), e)
+                        })?
+                        .complete(PREC),
+                ));
+            }
+        }
+
+        Ok(Self(nodes))
+    }
+}
+
+#[test]
+fn test() {
+    assert_eq!(
+        Nodes::from_str("sin(2) + 1").unwrap().as_ref(),
+        &[
+            Node::Function(Function::Sine),
+            Node::ParenthesisStart,
+            Node::Number(Float::with_val(PREC, 2)),
+            Node::ParenthesisEnd,
+            Node::Operator(Operator::Plus),
+            Node::Number(Float::with_val(PREC, 1))
+        ],
+    )
+}

src/nodes/tests.rs

@@ -1,78 +1,40 @@
 use core::f64;
 use std::str::FromStr;
 
-use rug::Float;
+use crate::nodes::Nodes;
 
-use crate::nodes::{Function, Node, Nodes, Operator, PREC};
+fn eval(s: &str) -> f64 {
+    Nodes::from_str(s).unwrap().evaluate().unwrap().to_f64()
+}
+
+#[test]
+fn plus_minus_order() {
+    assert_eq!(eval("1 - 4 - 5"), -8.);
+    assert_eq!(eval("1 - 4 + 5"), 2.);
+    assert_eq!(eval("1 + 4 - 5"), 0.);
+}
 
 #[test]
 fn e_edge_case() {
-    assert_eq!(Nodes::from_str("1e-1").unwrap().evaluate().to_f64(), 0.1)
+    assert_eq!(eval("1e-1"), 0.1)
 }
 
 #[test]
 fn implicit_mult() {
-    assert_eq!(
-        Nodes::from_str("10 sin(10)").unwrap().evaluate().to_f64(),
-        -5.440211108893698
-    );
+    assert_eq!(eval("10 sin(10)"), -5.440211108893698);
 
-    assert_eq!(
-        Nodes::from_str("(10)(10)").unwrap().evaluate().to_f64(),
-        100.,
-    )
+    assert_eq!(eval("(10)(10)"), 100.,)
 }
 
 #[test]
 fn constants() {
-    assert_eq!(
-        Nodes::from_str("c").unwrap().evaluate().to_f64(),
-        299792458.
-    );
-    assert_eq!(
-        Nodes::from_str("A").unwrap().evaluate().to_f64(),
-        6.02214076e23
-    );
-    assert_eq!(
-        Nodes::from_str("pi").unwrap().evaluate().to_f64(),
-        f64::consts::PI
-    );
+    assert_eq!(eval("c"), 299792458.);
+    assert_eq!(eval("A"), 6.02214076e23);
+    assert_eq!(eval("pi"), f64::consts::PI);
 }
 
 #[test]
 fn unary_operators() {
-    assert_eq!(Nodes::from_str("-10").unwrap().evaluate().to_f64(), -10.);
-    assert_eq!(Nodes::from_str("+10").unwrap().evaluate().to_f64(), 10.);
-}
-
-#[test]
-fn test_nodes_to_num() {
-    assert_eq!(
-        Nodes(vec![
-            Node::Function(Function::Sine),
-            Node::ParenthesisStart,
-            Node::Number(Float::with_val(PREC, 2)),
-            Node::ParenthesisEnd,
-            Node::Operator(Operator::Plus),
-            Node::Number(Float::with_val(PREC, 1))
-        ])
-        .evaluate()
-        .to_f64(),
-        1.9092974268256817,
-    );
-}
-
-#[test]
-fn test_nodes_from_str() {
-    assert_eq!(
-        Nodes::from_str("sin(2) + 1").unwrap().as_ref(),
-        &[
-            Node::Function(Function::Sine),
-            Node::ParenthesisStart,
-            Node::Number(Float::with_val(PREC, 2)),
-            Node::ParenthesisEnd,
-            Node::Operator(Operator::Plus),
-            Node::Number(Float::with_val(PREC, 1))
-        ],
-    )
+    assert_eq!(eval("-10"), -10.);
+    assert_eq!(eval("+10"), 10.);
 }