Enhance the help command to print info about a given unit

numbat-cli/src/main.rs

@@ -370,6 +370,15 @@ impl Cli {
                                 println!();
                             }
                             _ => {
+                                if let Some(keyword) = line.strip_prefix("info") {
+                                    let help = self
+                                        .context
+                                        .lock()
+                                        .unwrap()
+                                        .print_info_for_keyword(keyword.trim());
+                                    println!("{}", ansi_format(&help, true));
+                                    continue;
+                                }
                                 let result = self.parse_and_evaluate(
                                     &line,
                                     CodeSource::Text,

numbat-cli/tests/integration.rs

@@ -1,6 +1,7 @@
 use std::path::Path;
 
 use assert_cmd::Command;
+use predicates::boolean::PredicateBooleanExt;
 
 fn numbat() -> Command {
     let module_path = Path::new(&std::env::var_os("CARGO_MANIFEST_DIR").unwrap()).join("modules");
@@ -125,3 +126,15 @@ fn help_text() {
             "Energy of red photons: 1.87855 eV",
         ));
 }
+
+#[test]
+fn info_text() {
+    numbat().write_stdin("info g0").assert().success().stdout(
+        predicates::str::contains("Standard acceleration of gravity on earth")
+            .and(predicates::str::contains("9.80665 m/s²")),
+    );
+
+    numbat().write_stdin("info C").assert().success().stdout(
+        predicates::str::contains("Coulomb").and(predicates::str::contains("1 coulomb = ")),
+    );
+}

numbat-wasm/src/lib.rs

@@ -175,6 +175,11 @@ impl Numbat {
         self.format(&help_markup(), true).into()
     }
 
+    pub fn print_info(&mut self, keyword: &str) -> JsValue {
+        let output = self.ctx.print_info_for_keyword(keyword);
+        self.format(&output, false).into()
+    }
+
     pub fn get_completions_for(&self, input: &str) -> Vec<JsValue> {
         self.ctx
             .get_completions_for(input, false)

numbat-wasm/www/index.js

@@ -68,8 +68,14 @@ function interpret(input) {
   } else if (input_trimmed == "help" || input_trimmed == "?") {
     output = numbat.help();
   } else {
-    var result = numbat.interpret(input);
-    output = result.output;
+    var result = {is_error: false};
+    if (input_trimmed.startsWith("info")) {
+      var keyword = input_trimmed.substring(4).trim();
+      output = numbat.print_info(keyword);
+    } else {
+      result = numbat.interpret(input);
+      output = result.output;
+    }
 
     if (!result.is_error) {
         combined_input += input.trim() + "⏎";

numbat/modules/math/constants.nbt

@@ -2,12 +2,23 @@ use core::scalar
 
 ### Mathematical
 
-let pi = 3.14159265358979323846264338327950288
-let π = pi
+@name("Pi")
+@url("https://en.wikipedia.org/wiki/Pi")
+@aliases(pi)
+let π = 3.14159265358979323846264338327950288
+
+@name("Tau")
+@url("https://en.wikipedia.org/wiki/Turn_(angle)#Tau_proposals")
 let τ = 2 π
+
+@name("Euler's number")
+@url("https://en.wikipedia.org/wiki/E_(mathematical_constant)")
 let e = 2.71828182845904523536028747135266250
+
+@name("Golden ratio")
+@url("https://en.wikipedia.org/wiki/Golden_ratio")
+@aliases(golden_ratio)
 let φ = 1.61803398874989484820458683436563811
-let golden_ratio = φ
 
 ### Named numbers
 
@@ -41,16 +52,23 @@ unit quadrillion = 10^15
 @url("https://en.wikipedia.org/wiki/Quintillion")
 unit quintillion = 10^18
 
+@name("Googol")
+@url("https://en.wikipedia.org/wiki/Googol")
 let googol =  10^100
 
 ### Unicode fractions
 
+@name("One half")
+@url("https://en.wikipedia.org/wiki/One_half")
+@aliases(half, semi)
 let ½ = 1 / 2
 
 let ⅓ = 1 / 3
 let ⅔ = 2 / 3
 
+@aliases(quarter)
 let ¼ = 1 / 4
+
 let ¾ = 3 / 4
 
 let ⅕ = 1 / 5
@@ -72,11 +90,59 @@ let ⅑ = 1 / 9
 
 let ⅒ = 1 / 10
 
-#### Colloquial
+#### Integers and colloquial names
+
+@name("One")
+@url("https://en.wikipedia.org/wiki/1")
+let one = 1
+
+@name("Two")
+@url("https://en.wikipedia.org/wiki/2")
+@aliases(double)
+let two = 2
+
+@name("Three")
+@url("https://en.wikipedia.org/wiki/3")
+@aliases(triple)
+let three = 3
+
+@name("Four")
+@url("https://en.wikipedia.org/wiki/4")
+@aliases(quadruple)
+let four = 4
+
+@name("Five")
+@url("https://en.wikipedia.org/wiki/5")
+let five = 5
+
+@name("Six")
+@url("https://en.wikipedia.org/wiki/6")
+let six = 6
+
+@name("Seven")
+@url("https://en.wikipedia.org/wiki/7")
+let seven = 7
+
+@name("Eight")
+@url("https://en.wikipedia.org/wiki/8")
+let eight = 8
+
+@name("Nine")
+@url("https://en.wikipedia.org/wiki/9")
+let nine = 9
+
+@name("Ten")
+@url("https://en.wikipedia.org/wiki/10")
+let ten = 10
+
+@name("Eleven")
+@url("https://en.wikipedia.org/wiki/11")
+let eleven = 11
+
+@name("Twelve")
+@url("https://en.wikipedia.org/wiki/12")
+let twelve = 12
 
-let quarter = 1 / 4
-let half = 1 / 2
-let semi = 1 / 2
-let double = 2
-let triple = 3
+@name("Dozen")
+@url("https://en.wikipedia.org/wiki/Dozen")
 unit dozen = 12

numbat/modules/physics/constants.nbt

@@ -1,80 +1,94 @@
 use math::functions
 use units::si
 
-### Physics constants
-
-# The speed of light in vacuum
+@name("Speed of light in vacuum")
+@url("https://en.wikipedia.org/wiki/Speed_of_light")
+@aliases(c)
 let speed_of_light: Velocity = 299_792_458 m / s
-let c = speed_of_light
 
-# The Newtonian constant of gravitation
+@name("Newtonian constant of gravitation")
+@url("https://en.wikipedia.org/wiki/Gravitational_constant")
+@aliases(G)
 let gravitational_constant: Force × Length^2 / Mass^2 =  6.67430e-11 m³ / (kg s²)
-let G = gravitational_constant
 
-# Standard acceleration of gravity on earth
+@name("Standard acceleration of gravity on earth")
+@url("https://en.wikipedia.org/wiki/Gravity_of_Earth")
+@aliases(g0)
 let gravity: Acceleration = 9.80665 m / s²
-let g0 = gravity
 
-# The Planck constant
+@name("Planck constant")
+@url("https://en.wikipedia.org/wiki/Planck_constant")
+@aliases(ℎ)
 let planck_constant: Action = 6.62607015e-34 J / Hz
-let ℎ = planck_constant
 
-# The reduced Planck constant
+@name("Reduced Planck constant")
+@url("https://en.wikipedia.org/wiki/Planck_constant#Reduced_Planck_constant_%E2%84%8F")
+@aliases(h_bar)
 let ℏ: AngularMomentum = planck_constant / 2π
-let h_bar = ℏ
 
-# Mass of the electron
+@name("Electron mass")
+@url("https://en.wikipedia.org/wiki/Electron_mass")
 let electron_mass: Mass = 9.1093837015e-31 kg
 
-# Elementary charge (charge of the electron)
+@name("Elementary charge")
+@url("https://en.wikipedia.org/wiki/Elementary_charge")
+@aliases(electron_charge)
 let elementary_charge: ElectricCharge =  1.602176634e-19 C
-let electron_charge: ElectricCharge = elementary_charge
 
-# Magnetic constant (vacuum magnetic permeability)
+@name("Vacuum permeability / magnetic constant")
+@url("https://en.wikipedia.org/wiki/Vacuum_permeability")
+@aliases(µ0,mu0)
 let magnetic_constant: MagneticPermeability =  1.25663706212e-6 N / A²
-let µ0 = magnetic_constant
-let mu0 = magnetic_constant
 
-# Electric constant ( vacuum electric permittivity)
+@name("Vacuum electric permittivity / electric constant")
+@url("https://en.wikiversity.org/wiki/Electric_constant")
+@aliases(ε0,eps0)
 let electric_constant: ElectricPermittivity = 8.8541878128e-12 F / m
-let ε0 = electric_constant
-let eps0 = electric_constant
 
-# Bohr magneton
+@name("Bohr magneton")
+@aliases(µ_B)
+@url("https://en.wikipedia.org/wiki/Bohr_magneton")
 let bohr_magneton: Energy / MagneticFluxDensity = 9.2740100783e-24 J / T
-let µ_B = bohr_magneton
 
-# Fine structure constant
+@name("Fine structure constant")
+@url("https://en.wikipedia.org/wiki/Fine-structure_constant")
+@aliases(α, alpha)
 let fine_structure_constant: Scalar = 7.2973525693e-3
-let α = fine_structure_constant
-let alpha = fine_structure_constant
 
-# Proton mass
+@name("Proton mass")
+@url("https://en.wikipedia.org/wiki/Proton")
 let proton_mass: Mass =  1.67262192369e-27 kg
 
-# Neutron mass
+@name("Neutron mass")
+@url("https://en.wikipedia.org/wiki/Neutron")
 let neutron_mass: Mass = 1.67492749804e-27 kg
 
-# Avogadro constant
+@name("Avogadro constant")
+@url("https://en.wikipedia.org/wiki/Avogadro_constant")
+@aliases(N_A)
 let avogadro_constant: 1 / AmountOfSubstance = 6.02214076e23 / mol
-let N_A = avogadro_constant
 
-# Boltzmann constant
+@name("Boltzmann constant")
+@url("https://en.wikipedia.org/wiki/Boltzmann_constant")
+@aliases(k_B)
 let boltzmann_constant: Energy / Temperature = 1.380649e-23 J / K
-let k_B = boltzmann_constant
 
-# Stefan-Boltzmann constant
+@name("Stefan-Boltzmann constant")
+@url("https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law")
 let stefan_boltzmann_constant: Power / (Area × Temperature^4) = 2 π^5 k_B^4 / (15 planck_constant^3 c^2)
 
-# Ideal gas constant
+@name("Ideal gas constant")
+@url("https://en.wikipedia.org/wiki/Gas_constant")
+@aliases(R)
 let gas_constant: Energy / (AmountOfSubstance × Temperature) = 8.31446261815324 J / (K mol)
-let R = gas_constant
 
-# Bohr radius
+@name("Bohr radius")
+@url("https://en.wikipedia.org/wiki/Bohr_radius")
+@aliases(a0)
 let bohr_radius: Length = 4 pi ε0 ℏ^2 / (electron_charge^2 electron_mass)
-let a0 = bohr_radius
 
-# Rydberg constant
+@name("Rydberg constant")
+@url("https://en.wikipedia.org/wiki/Rydberg_constant")
 let rydberg_constant: Wavenumber = (electron_mass electron_charge^4) / (8 ε0^2 ℎ^3 c)
 
 @name("Rydberg unit of energy")

numbat/src/ast.rs

@@ -295,6 +295,7 @@ pub enum Statement {
         identifier: String,
         expr: Expression,
         type_annotation: Option<TypeAnnotation>,
+        decorators: Vec<Decorator>,
     },
     DefineFunction {
         function_name_span: Span,
@@ -440,11 +441,13 @@ impl ReplaceSpans for Statement {
                 identifier,
                 expr,
                 type_annotation,
+                decorators,
             } => Statement::DefineVariable {
                 identifier_span: Span::dummy(),
                 identifier: identifier.clone(),
                 expr: expr.replace_spans(),
                 type_annotation: type_annotation.as_ref().map(|t| t.replace_spans()),
+                decorators: decorators.clone(),
             },
             Statement::DefineFunction {
                 function_name_span: _,