Updated TODO

TODO.md

@@ -1,38 +1,34 @@
 ## Version Bump checklist
+ - TODO: build and publish script
  - update Cargo.toml
  - run cargo test
  - commit
- - git tag -a v1.0.0 -m "Version 1.0.0"
- - git push
- - git push origin v1.0.0
+ - push
+ - merge
+ - git tag -a v1.0.0 -m "Version 1.0.0" on merge commit
  - cargo publish
  - Update packages
 
 
-
 ## Pre-release
- - Fix linelocation (consistent, what does an operator's linelocation mean?)
  - Tuple operations
  - we don't need vectors as arguments to operators
- - Assignment tests
+ - Fix linelocation when evaluating functions
 
 ## Parser
- - Better error when `sin = 2`
  - Should functions be operators?
  - Binary, hex, octal numbers
 
 
 ## General
+ - Better tests (assignment, many expressions in one context)
  - Optional config file
  - Optional history file
- - daisyrc file
  - Compile to WASM, publish a webapp
  - evaluate straight from command line
- - Auto-push to crates.io
  - Package for debian
 
 
-
 ## Internals
  - Non-recursive treeify
  - Faster factorial function. Maybe use gamma instead?
@@ -40,7 +36,6 @@
  - Remove rug dependency (too big, incompatible)
 
 ## Math Features
- - Dice
  - Mean, Median, Min
  - Arbitrary base logarithm
  - Derivatives
@@ -48,20 +43,16 @@
  - Complex numbers
  - acot/acoth functions
  - Sums and products with functional arguments
+ - Add functions: gcd, inverse mod, dice
 
 ## Prompt
+ - Fix terminal color detection
  - Live syntax/output (like firefox js terminal)
- - Syntax highlight input and output
+ - Syntax highlighting
  - fish-style tab completion
  - Numbered expressions, history recall
- - Color configuration
  - Enable/disable unit sets (defaults?)
  - Consistent unit ordering
- - Better linelocation
-   - we shouldn't need to re-print user input on evaluation errors, red arrows should adjust themselves to the prettyprinted string
- - Backend-independent colorful printing
-   - Better colors in error texts
- - Better substitution. Consistent: when ascii, when unicode?
  - Command to list substitutions
 
 ## Units

src/command/mod.rs

@@ -224,7 +224,7 @@ pub fn do_command(
 			if args.len() != 2 {
 				return FormattedText::new(
 					format!(
-						"[c]{first}[n] [t]takes exactly two arguments.[n]\n\n",
+						"[c]{first}[n] [t]takes exactly one argument.[n]\n\n",
 					)
 				);
 			}

src/context.rs

@@ -19,7 +19,7 @@ pub struct Config {
 	// with prettier unicode alternatives?
 	//
 	// Automatically disabled if enable_unicode is off.
-	//pub enable_substituion: bool,
+	pub enable_substituion: bool,
 
 	// Should we print simple powers
 	// as unicode superscript chars?
@@ -38,7 +38,7 @@ impl Config {
 	pub fn new() -> Config {
 		Config{
 			term_color_type: 2,
-			//enable_substituion: true,
+			enable_substituion: true,
 			//enable_unicode: true,
 			enable_super_powers: true,
 			enable_one_over_power: true
@@ -126,6 +126,7 @@ impl Context {
 		} else { panic!() }
 	}
 
+	// Can we define a new variable with this name?
 	pub fn valid_varible(&self, s: &str) -> bool {
 		if {
 			Function::from_string(s).is_some() ||
@@ -145,10 +146,17 @@ impl Context {
 		}
 	}
 
+	// Can we get a value fro mthis variable name?
 	pub fn is_varible(&self, s: &str) -> bool {
 		return {
-			self.valid_varible(s) &&
-			(self.variables.contains_key(s) || self.shadow.contains_key(s))
+			(
+				s == "ans" &&
+				self.history.len() != 0
+			) ||
+			(
+				self.valid_varible(s) &&
+				(self.variables.contains_key(s) || self.shadow.contains_key(s))
+			)
 		};
 	}
 

src/entrypoint/unix/promptbuffer.rs

@@ -1,11 +1,12 @@
 use std::collections::VecDeque;
 use std::io::Write;
 use termion::raw::RawTerminal;
-use termion::color;
-use termion::style;
+use crate::formattedtext;
 use crate::parser::substitute_cursor;
 use crate::context::Context;
 
+const PROMPT_STR: &str = "==> ";
+
 #[derive(Debug)]
 pub struct PromptBuffer {
 	// History
@@ -38,30 +39,11 @@ impl PromptBuffer {
 
 	// Same as write_primpt, but pretends there is no cursor
 	pub fn write_prompt_nocursor(&mut self, context: &Context, stdout: &mut RawTerminal<std::io::Stdout>) -> Result<(), std::io::Error> {
-		// Draw prettyprinted expression
-		let (_, s) = substitute_cursor(context, &self.get_contents(), self.buffer.chars().count());
-
-		write!(
-			stdout, "\r{}{}==>{}{} {}",
-			style::Bold,
-			color::Fg(color::Blue),
-			color::Fg(color::Reset),
-			style::Reset,
-			s
-		)?;
-
-		// If this string is shorter, clear the remaining old one.
-		if s.chars().count() < self.last_print_len {
-			write!(
-				stdout, "{}{}",
-				" ".repeat(self.last_print_len - s.chars().count()),
-				termion::cursor::Left((self.last_print_len - s.chars().count()) as u16)
-			)?;
-		}
-
-		self.last_print_len = s.chars().count();
-		stdout.flush()?;
-		return Ok(());
+		let tmp = self.cursor;
+		self.cursor = 0;
+		let r = self.write_prompt(context, stdout);
+		self.cursor = tmp;
+		return r;
 	}
 
 	pub fn write_prompt(&mut self, context: &Context, stdout: &mut RawTerminal<std::io::Stdout>) -> Result<(), std::io::Error> {
@@ -69,38 +51,30 @@ impl PromptBuffer {
 		let i = if l == 0 {0} else {l - self.cursor};
 
 		// Draw prettyprinted expression
-		let (display_cursor, s) = substitute_cursor(context, &self.get_contents(), i);
-
+		let (display_c, s) = substitute_cursor(context, &self.get_contents(), i);
+	
 		write!(
-			stdout, "\r{}{}==>{}{} {}",
-			style::Bold,
-			color::Fg(color::Blue),
-			color::Fg(color::Reset),
-			style::Reset,
+			stdout, "\r{}{PROMPT_STR}{}{}",
+			formattedtext::format_map('p', context).unwrap(),
+			formattedtext::format_map('n', context).unwrap(),
 			s
 		)?;
 
 		// If this string is shorter, clear the remaining old one.
 		if s.chars().count() < self.last_print_len {
-			write!(
-				stdout, "{}{}",
-				" ".repeat(self.last_print_len - s.chars().count()),
-				termion::cursor::Left((self.last_print_len - s.chars().count()) as u16)
-			)?;
-		}
-
-
-		// Move cursor to correct position
-		if display_cursor != 0 {
 			write!(
 				stdout, "{}",
-				termion::cursor::Left(display_cursor as u16)
+				" ".repeat(self.last_print_len - s.chars().count()),
 			)?;
-			stdout.flush()?;
 		}
-		self.last_print_len = s.chars().count();
+
+		write!(
+			stdout, "\r{}",
+			termion::cursor::Right((display_c + PROMPT_STR.chars().count()) as u16)
+		)?;
 
 		stdout.flush()?;
+		self.last_print_len = s.chars().count();
 
 		return Ok(());
 	}

src/entrypoint/unix/unix.rs

@@ -23,11 +23,11 @@ pub fn main() -> Result<(), std::io::Error> {
 	// Set color compatibilty
 	let term_colors = stdout.available_colors().unwrap_or(0);
 	if term_colors >= 256 {
-		context.config.term_color_type = 2
+		context.config.term_color_type = 2;
 	} else if term_colors >= 8 {
-		context.config.term_color_type = 1
+		context.config.term_color_type = 1;
 	} else {
-		context.config.term_color_type = 0
+		context.config.term_color_type = 0;
 	}
 
 	context.config.check();

src/evaluate/operator.rs

@@ -75,12 +75,26 @@ pub fn eval_operator(context: &mut Context, g: &Expression) -> Result<Option<Exp
 			if let Expression::Quantity(la, a) = a {
 				if let Expression::Quantity(lb, b) = b {
 					if !a.unit.compatible_with(&b.unit) {
+						let a = a.convert_to_base().unit;
+						let b = b.convert_to_base().unit;
+
+						let a_s: String;
+						let b_s: String;
+						if a.unitless() {
+							a_s = String::from("scalar");
+						} else {
+							a_s = a.display(context);
+						}
+
+						if b.unitless() {
+							b_s = String::from("scalar");
+						} else {
+							b_s = b.display(context);
+						}
+
 						return Err((
 							*la + *lb + *op_loc,
-							DaisyError::IncompatibleUnits(
-								a.convert_to_base().unit.display(context),
-								b.convert_to_base().unit.display(context)
-							)
+							DaisyError::IncompatibleUnits(a_s, b_s)
 						));
 					}
 					return Ok(Some(Expression::Quantity(*la + *lb + *op_loc, a.clone() + b.clone())));
@@ -98,12 +112,24 @@ pub fn eval_operator(context: &mut Context, g: &Expression) -> Result<Option<Exp
 			if let Expression::Quantity(la, a) = a {
 				if let Expression::Quantity(lb, b) = b {
 					if !a.unit.compatible_with(&b.unit) {
+
+						let a_s: String;
+						let b_s: String;
+						if a.unitless() {
+							a_s = String::from("scalar");
+						} else {
+							a_s = a.display(context);
+						}
+
+						if b.unitless() {
+							b_s = String::from("scalar");
+						} else {
+							b_s = b.display(context);
+						}
+
 						return Err((
 							*la + *lb + *op_loc,
-							DaisyError::IncompatibleUnits(
-								a.convert_to_base().unit.display(context),
-								b.convert_to_base().unit.display(context)
-							)
+							DaisyError::IncompatibleUnits(a_s, b_s)
 						));
 					}
 					return Ok(Some(Expression::Quantity(*la + *lb + *op_loc, a.clone() - b.clone())));
@@ -162,6 +188,11 @@ pub fn eval_operator(context: &mut Context, g: &Expression) -> Result<Option<Exp
 					if va.fract() != Quantity::new_rational(0f64).unwrap() { return Err((*la + *lb + *op_loc, DaisyError::BadMath)); }
 					if vb.fract() != Quantity::new_rational(0f64).unwrap() { return Err((*la + *lb + *op_loc, DaisyError::BadMath)); }
 
+
+					let o = va.clone() % vb.clone();
+					if o.is_nan() {return Err((*la + *lb + *op_loc, DaisyError::BadMath));}
+
+
 					return Ok(Some(Expression::Quantity(*la + *lb + *op_loc, va.clone() % vb.clone())));
 				} else { return Ok(None); }
 			} else { return Ok(None); }
@@ -176,12 +207,26 @@ pub fn eval_operator(context: &mut Context, g: &Expression) -> Result<Option<Exp
 				if let Expression::Quantity(lb, vb) = b {
 					let n = va.clone().convert_to(vb.clone());
 					if n.is_none() {
+						let va = va.convert_to_base().unit;
+						let vb = vb.convert_to_base().unit;
+
+						let a_s: String;
+						let b_s: String;
+						if va.unitless() {
+							a_s = String::from("scalar");
+						} else {
+							a_s = a.display(context);
+						}
+
+						if vb.unitless() {
+							b_s = String::from("scalar");
+						} else {
+							b_s = b.display(context);
+						}
+
 						return Err((
 							*la + *lb + *op_loc,
-							DaisyError::IncompatibleUnits(
-								va.convert_to_base().unit.display(context),
-								vb.convert_to_base().unit.display(context)
-							)
+							DaisyError::IncompatibleUnits(a_s, b_s)
 						));
 					}
 					return Ok(Some(Expression::Quantity(*la + *lb + *op_loc, n.unwrap())));

src/formattedtext.rs

@@ -22,7 +22,8 @@ impl ToString for FormattedText {
 fn format_map_none(c: char) -> Option<String> {
 	Some(match c {
 		'n'|'i'|'t'|'a'|
-		'e'|'c'|'s'|'r'
+		'e'|'c'|'s'|'r'|
+		'p'
 		=> { "".to_string() },
 		_ => { return None }
 	})
@@ -37,34 +38,39 @@ fn format_map_ansi(c: char) -> Option<String> {
 		'i' => { // Normal italic text
 			format!("{}{}", color::Fg(color::Reset), color::Bg(color::Reset))
 		},
-		't' => { // Title text
+		't' => { // Title text (should be cyan)
 			format!("{}{}", color::Fg(color::AnsiValue(6)), color::Bg(color::Reset))
 		},
-		'a' => { // Colored text
+		'a' => { // Colored text (should be pink)
 			format!("{}{}", color::Fg(color::AnsiValue(5)), color::Bg(color::Reset))
 		},
-		'e' => { // Error titles
+		'e' => { // Error titles (should be red)
 			format!("{}{}", color::Fg(color::AnsiValue(1)), color::Bg(color::Reset))
 		},
-		'c' => { // Console text
+		'c' => { // Console text (inverted black on white)
 			format!("{}{}", color::Fg(color::AnsiValue(0)), color::Bg(color::AnsiValue(7)))
 		},
-		's' => { // Repeat prompt (how => is styled)
-			format!("{}{}", color::Fg(color::AnsiValue(2)), color::Bg(color::Reset))
-		},
-		'r' => { // Result prompt (how = is styled)
+		'p' => { // Input prompt (how ==> is styled) (should be blue)
 			format!("{}{}", color::Fg(color::AnsiValue(4)), color::Bg(color::Reset))
 		},
+		's' => { // Repeat prompt (how => is styled) (should be pink)
+			format!("{}{}", color::Fg(color::AnsiValue(5)), color::Bg(color::Reset))
+		},
+		'r' => { // Result prompt (how = is styled) (should be green)
+			format!("{}{}", color::Fg(color::AnsiValue(2)), color::Bg(color::Reset))
+		},
 
 		_ => { return None }
 	})
 }
 
 
+// style::reset also resets color.
+// Make sure color comes AFTER style reset.
 fn format_map_full(c: char) -> Option<String> {
 	Some(match c {
 		'n' => { // Normal text
-			format!("{}{}", color::Fg(color::Reset), style::Reset)
+			format!("{}{}", style::Reset, color::Fg(color::Reset))
 		},
 		'i' => { // Normal italic text
 			format!("{}{}", color::Fg(color::Reset), style::Italic)
@@ -73,7 +79,7 @@ fn format_map_full(c: char) -> Option<String> {
 			format!("{}{}", color::Fg(color::Magenta), style::Bold)
 		},
 		'a' => { // Colored text
-			format!("{}{}", color::Fg(color::Magenta), style::Reset)
+			format!("{}{}", style::Reset, color::Fg(color::Magenta))
 		},
 		'e' => { // Error titles
 			format!("{}{}", color::Fg(color::Red), style::Bold)
@@ -81,6 +87,9 @@ fn format_map_full(c: char) -> Option<String> {
 		'c' => { // Console text
 			format!("{}{}", color::Fg(color::LightBlack), style::Italic)
 		},
+		'p' => { // Input prompt (how ==> is styled)
+			format!("{}{}", color::Fg(color::Blue), style::Bold)
+		},
 		's' => { // Repeat prompt (how => is styled)
 			format!("{}{}", color::Fg(color::Magenta), style::Bold)
 		},
@@ -88,17 +97,24 @@ fn format_map_full(c: char) -> Option<String> {
 			format!("{}{}", color::Fg(color::Green), style::Bold)
 		},
 
+
 		_ => { return None }
 	})
 }
 
+pub fn format_map(c: char, context: &Context) -> Option<String> {
+	match context.config.term_color_type {
+		0 => format_map_none(c),
+		1 => format_map_ansi(c),
+		2 => format_map_full(c),
+		_ => unreachable!("Invalid term_color_type")
+	}
+}
+
 
 impl FormattedText {
 	pub fn newline(stdout: &mut RawTerminal<std::io::Stdout>) -> Result<(), std::io::Error> {
-		write!(
-			stdout,
-			"\r\n",
-		)?;
+		write!(stdout, "\n")?;
 		return Ok(());
 	}
 }
@@ -145,12 +161,7 @@ impl FormattedText {
 					match (a, b) {
 						(c, ']') => { // Normal text
 
-							let q = match context.config.term_color_type {
-								0 => format_map_none(c),
-								1 => format_map_ansi(c),
-								2 => format_map_full(c),
-								_ => unreachable!("Invalid term_color_type")
-							};
+							let q = format_map(c, context);
 
 							if q.is_some() {
 								s.push_str(&q.unwrap());
@@ -173,7 +184,7 @@ impl FormattedText {
 			}
 		}
 
-		write!(stdout, "{}", s)?;
+		write!(stdout, "\r{}", s)?;
 		return Ok(());
 	}
 }

src/parser/expression/expression.rs

@@ -11,6 +11,23 @@ use super::super::LineLocation;
 #[derive(Debug)]
 #[derive(Clone)]
 pub enum Expression {
+	// Meaning of `LineLocation`:
+	//
+	// For Variables, Constants, Quantities, Tuples:
+	// If this expression was parsed, LineLocation is what part of the prompt was parsed to get this expression
+	// If this expression is the result of a calculation, LineLocaion is the sum of the LineLocations of
+	//	all expressions used to make it. In other words, it points to the part of the prompt that was evaluated
+	//	to get this new expression.
+	//
+	// For Operators:
+	// Linelocation points to the operator's position in the prompt.
+	// If this is a function, it points to the function name.
+	// If this is `+`, `!`, or etc, it points to that character.
+	// Operator arguments are NOT included in this linelocation.
+	//
+	//
+	// All the above rules are implemented when parsing and evaluating expressions.
+
 	Variable(LineLocation, String),
 	Quantity(LineLocation, Quantity),
 	Constant(LineLocation, Constant),

src/parser/mod.rs

@@ -21,8 +21,10 @@ pub fn parse(
 	context: &Context, s: &String
 ) -> Result<Expression, (LineLocation, DaisyError)> {
 
-	let expressions = stage::tokenize(context, s);
-	let (_, expressions) = stage::find_subs(expressions);
+	let mut expressions = stage::tokenize(context, s);
+	if context.config.enable_substituion {
+		(_, expressions) = stage::find_subs(expressions);
+	}
 	let g = stage::groupify(context, expressions)?;
 	let g = stage::treeify(context, g)?;
 
@@ -33,7 +35,14 @@ pub fn parse_no_context(s: &String) -> Result<Expression, (LineLocation, DaisyEr
 	parse(&Context::new(), s)
 }
 
+
+
+// Substitiution replaces certain string with pretty unicode characters.
+// When it is enabled, ALL input strings are substituted. Variable and
+// operator tokens use the replaced string value. Make sure both the
+// original and the replaced strings are handled correctly by the parser.
 pub fn substitute(context: &Context, s: &String) -> String {
+	if !context.config.enable_substituion { return s.clone(); }
 	let (_, s) = substitute_cursor(context, s, s.chars().count());
 	return s;
 }
@@ -43,34 +52,45 @@ pub fn substitute_cursor(
 	s: &String, // The string to substitute
 	c: usize    // Location of the cursor right now
 ) -> (
-	usize,  // Location of cursor in substituted string
+	usize,  // New cursor
 	String  // String with substitutions
 ) {
+
+	if !context.config.enable_substituion { return (c, s.clone()); }
 	if s == "" { return (c, s.clone()) }
+	
+	
 	let mut new_s = s.clone();
 
-	let l = s.chars().count();
 	let expressions = stage::tokenize(context, s);
 	let (mut subs, _) = stage::find_subs(expressions);
-	let mut new_c = l - c;
+	let mut new_c = c.clone();
 
 	while subs.len() > 0 {
-		let r = subs.pop_back().unwrap();
 		// Apply substitutions in reverse order
+		// r is the current substitution: (linelocation, string)
+		let r = subs.pop_back().unwrap();
 
 		if { // Don't substitute if our cursor is inside the substitution
 			c >= r.0.pos &&
 			c < r.0.pos+r.0.len
 		} { continue; }
 
-		if c < r.0.pos {
-			let ct = r.1.chars().count();
-			if ct >= r.0.len {
-				if new_c >= ct - r.0.len {
-					new_c += ct - r.0.len
-				}
-			} else {
-				new_c -= r.0.len - ct
+		// If this substitution is before our cursor,
+		// we need to adjust our cursor's position.
+		if c > r.0.pos {
+			let c_o = r.0.len; // Old length 
+			let c_n = r.1.chars().count(); // New length
+
+			if c_n > c_o {
+				// Move cursor right by difference
+				new_c += c_n - c_o;
+
+			} else if c_n < c_o {
+				// Move cursor left by difference
+				if new_c >= c_o - c_n {
+					new_c -= c_o - c_n;
+				} else { new_c = 0; }
 			}
 		}
 

src/parser/stage/find_subs.rs

@@ -6,11 +6,69 @@ use super::super::{
 };
 
 
+fn sub_string(s: &str) -> Option<&'static str> {
+	let r = match s {
+
+		/* Only found in operator tokens */
+
+		"*"    => "×",
+		"/"    => "÷",
+		"sqrt" => "√",
+		"rt"   => "√",
+
+
+
+		/* Only found in word tokens */
+
+		// Greek letters
+		"alpha"   => "α",
+		"beta"    => "β",
+		"gamma"   => "γ",
+		"delta"   => "δ",
+		"epsilon" => "ε",
+		"zeta"    => "ζ",
+		"eta"     => "η",
+		"theta"   => "θ",
+		//"iota"    => {Some("ι")}, // looks just like i
+		//"kappa"   => {Some("κ")}, // looks just like k
+		"lambda"  => "λ",
+		"mu"      => "μ",
+		//"nu"      => {Some("ν")}, // looks just like v
+		"xi"      => "ξ",
+		//"omicron" => {Some("ο")}, // looks exactly like o
+		"pi"      => "π",
+		"rho"     => "ρ",
+		"sigma"   => "σ",
+		"tau"     => "τ",
+		//"upsilon" => {Some("υ")}, // looks just like u
+		"phi"     => "φ",
+		"chi"     => "χ",
+		//"psi"     => {Some("ψ")},  Conflict with pound / square inch
+		"omega"   => "ω",
+
+		// Constants
+		"epsilon_zero" => "ε₀",
+		"eps_zero"     => "ε₀",
+		"g_zero"       => "g₀",
+		"mu_zero"      => "μ₀",
+		"h_bar"        => "ℏ",
+
+		// Misc
+		"deg" => "°",
+
+		_ => { return None; }
+	};
+	return Some(r);
+}
+
+
+// Finds substitutions in an array of tokens.
+// Returns new token array and substitution list.
 pub fn find_subs(
 	mut g: VecDeque<Token>,
 ) -> (
-	VecDeque<(LineLocation, String)>,
-	VecDeque<Token>
+	VecDeque<(LineLocation, String)>, // List of substrings to replace (in order)
+	VecDeque<Token> // New token array, with updated strings and linelocations
 ) {
 
 	// Array of replacements
@@ -24,62 +82,19 @@ pub fn find_subs(
 	while g.len() > 0 {
 		let mut t = g.pop_front().unwrap();
 
+
 		let target: Option<&str> = match &mut t {
 			Token::Operator(_, s) => {
-				let target = match &s[..] {
-					"*" => {Some("×")},
-					"/" => {Some("÷")},
-					"sqrt"    => {Some("√")},
-					"rt"      => {Some("√")},
-					_ => {None}
-				};
+				let target = sub_string(s);
 
 				// Update token contents too.
-				// This makes sure that errors also contain the updated text.
+				// This makes errors and printouts use the updated string.
 				if target.is_some() { *s = String::from(target.unwrap()); }
 				target
 			},
 
 			Token::Word(_, s) => {
-				let target = match &s[..] {
-					// Greek letters
-					"alpha"   => {Some("α")},
-					"beta"    => {Some("β")},
-					"gamma"   => {Some("γ")},
-					"delta"   => {Some("δ")},
-					"epsilon" => {Some("ε")},
-					"zeta"    => {Some("ζ")},
-					"eta"     => {Some("η")},
-					"theta"   => {Some("θ")},
-					//"iota"    => {Some("ι")},
-					//"kappa"   => {Some("κ")},
-					"lambda"  => {Some("λ")},
-					"mu"      => {Some("μ")},
-					//"nu"      => {Some("ν")},
-					"xi"      => {Some("ξ")},
-					//"omicron" => {Some("ο")},
-					"pi"      => {Some("π")},
-					"rho"     => {Some("ρ")},
-					"sigma"   => {Some("σ")},
-					"tau"     => {Some("τ")},
-					//"upsilon" => {Some("υ")},
-					"phi"     => {Some("φ")},
-					"chi"     => {Some("χ")},
-					//"psi"     => {Some("ψ")},  Conflict with pound / square inch
-					"omega"   => {Some("ω")},
-
-					// Constants
-					"epsilon_zero" => {Some("ε₀")},
-					"eps_zero"     => {Some("ε₀")},
-					"g_zero"       => {Some("g₀")},
-					"mu_zero"      => {Some("μ₀")},
-					"h_bar"        => {Some("ℏ")},
-
-					// Misc
-					"deg" => {Some("°")}
-					_ => {None}
-				};
-
+				let target = sub_string(s);
 				if target.is_some() { *s = String::from(target.unwrap()); }
 				target
 			},
@@ -88,7 +103,7 @@ pub fn find_subs(
 		};
 
 		if target.is_none() {
-			// Even if nothing changed, we need to update token location
+			// Even if nothing changed, we need to update the new token's linelocation
 			let l = t.get_mut_linelocation();
 			*l = LineLocation{pos: l.pos - offset, len: l.len};
 		} else {

src/quantity/scalar/floatbase.rs

@@ -244,7 +244,7 @@ impl Rem<FloatBase> for FloatBase {
 			(!modulus.fract().unwrap().is_zero())
 		} { panic!() }
 
-		FloatBase{val : self.val.fract() % modulus.val.fract()}
+		FloatBase{val : self.val.trunc() % modulus.val.trunc()}
 	}
 }
 

src/quantity/scalar/scalar.rs

@@ -186,7 +186,7 @@ impl Scalar {
 	pub fn is_nan(&self) -> bool {
 		match self {
 			Scalar::Float {v} => {v.val.is_nan()},
-			Scalar::Rational {..} => {panic!()}
+			Scalar::Rational {..} => {false}
 		}
 	}
 

src/tests.rs

@@ -162,6 +162,7 @@ fn operators() {
 
 	good_expr("2", "6/3");
 	good_expr("2", "5%3");
+	good_expr("4", "2^5 mod 7");
 	good_expr("8", "5+3");
 	good_expr("64", "4^3");
 	good_expr("64", "4 ^ 3");
@@ -184,6 +185,7 @@ fn operators() {
 	bad_expr("1e5!");
 	bad_expr("0^(-1)");
 	bad_expr("pi!");
+	bad_expr("2.5 mod 8");
 }
 
 #[test]