Initial commit

.envrc

@@ -0,0 +1 @@
+use nix

.gitignore

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+/target
+/.direnv/

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "calculatey"
+version = "0.1.0"
+dependencies = [
+ "type-fn",
+]
+
+[[package]]
+name = "type-fn"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "204df419af3d8f4e9d597266dcb61672b915d7bff2727f96ad63e53657f794f8"

Cargo.toml

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+[package]
+name = "calculatey"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+type-fn = "0.1.2"

shell.nix

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+{ pkgs ? import <nixpkgs> {} }:
+pkgs.mkShell {
+  nativeBuildInputs = with pkgs; [
+    cargo
+    helix
+    rust-analyzer
+    cargo-watch
+  ];
+}

src/main.rs

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+use std::fmt::Display;
+
+static mut INDENTATION: u32 = 0;
+
+fn indentation() -> String {
+    unsafe {
+        let mut s = String::new();
+        for _ in 0..INDENTATION {
+            s += "| ";
+        }
+        s
+    }
+}
+
+fn indent() {
+    unsafe {
+        INDENTATION += 1;
+    }
+}
+fn unindent() {
+    unsafe {
+        INDENTATION -= 1;
+    }
+}
+
+pub type BExpr = Box<Expression>;
+
+#[derive(PartialEq, Clone, Debug)]
+pub enum Expression {
+    Num(f64),
+    Var(char),
+    Add(BExpr, BExpr),
+    Sub(BExpr, BExpr),
+    Mul(BExpr, BExpr),
+    Div(BExpr, BExpr),
+}
+
+impl Expression {
+    pub fn simplify(self) -> Expression {
+        println!("{}Simplifying {self:?}", indentation());
+        indent();
+        use Expression::*;
+        let r = match self {
+            Num(x) => Num(x),
+            Var(x) => Var(x),
+            Add(a, b) => match (a.simplify(), b.simplify()) {
+                (Num(a), Num(0.)) => Num(a).simplify(),
+                (Num(0.), Num(a)) => Num(a).simplify(),
+                (Num(a), Num(b)) => Num(a + b).simplify(),
+                (a, b) if a == b => Mul(Num(2.).wrap(), a.wrap()).simplify(),
+                (a, Mul(b, c)) => match (b.simplify(), c.simplify()) {
+                    (b, Num(c)) if a == b => Mul(Num(c + 1.).wrap(), a.wrap()).simplify(),
+                    (Num(b), c) if a == c => Mul(Num(b + 1.).wrap(), a.wrap()).simplify(),
+                    (b, c) => Add(a.wrap(), Mul(b.wrap(), c.wrap()).wrap()),
+                },
+                (Mul(b, c), a) => match (b.simplify(), c.simplify()) {
+                    (b, Num(c)) if a == b => Mul(Num(c + 1.).wrap(), a.wrap()).simplify(),
+                    (Num(b), c) if a == c => Mul(Num(b + 1.).wrap(), a.wrap()).simplify(),
+                    (b, c) => Add(a.wrap(), Mul(b.wrap(), c.wrap()).wrap()),
+                },
+                (a, b) => Add(a.wrap(), b.wrap()),
+            },
+            Sub(a, b) => match (a.simplify(), b.simplify()) {
+                (a, b) if a == b => Num(0.),
+                (a, b) => Sub(a.wrap(), b.wrap()),
+            },
+            Mul(a, b) => match (a.simplify(), b.simplify()) {
+                (Num(a), Num(b)) => Num(a * b),
+                (Num(0.), b) => Num(0.),
+                (a, Num(0.)) => Num(0.),
+                (Num(1.), b) => b,
+                (a, Num(1.)) => a,
+                (a, b) => Mul(a.wrap(), b.wrap()),
+            },
+            Div(a, b) => match (a.simplify(), b.simplify()) {
+                (a, Num(1.)) => a,
+                (Num(0.), b) => Num(0.),
+                (a, b) => Div(a.wrap(), b.wrap()),
+            },
+        };
+        unindent();
+        println!("{} => {r:?}", indentation());
+        r
+    }
+
+    pub fn wrap(self) -> Box<Self> {
+        Box::new(self)
+    }
+}
+
+impl Display for Expression {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        use Expression::*;
+        match self {
+            Num(x) => f.write_fmt(format_args!("{x}")),
+            Var(x) => f.write_fmt(format_args!("{x}")),
+            Add(a, b) => f.write_fmt(format_args!("({a} + {b})")),
+            Sub(a, b) => f.write_fmt(format_args!("({a} - {b})")),
+            Mul(a, b) => f.write_fmt(format_args!("{a} {b}")),
+            Div(a, b) => f.write_fmt(format_args!("({a} / {b})")),
+        }
+    }
+}
+
+fn main() {
+    use Expression::*;
+    println!(
+        "{}",
+        // 5 * (((5 * 5) + 1) + ((a + (a + a)) + a))
+        Mul(
+            Num(5.).wrap(),
+            Add(
+                Add(Mul(Num(5.).wrap(), Num(5.).wrap()).wrap(), Num(1.).wrap()).wrap(),
+                Add(
+                    Add(
+                        Var('a').wrap(),
+                        Add(Var('a').wrap(), Var('a').wrap()).wrap()
+                    )
+                    .wrap(),
+                    Var('a').wrap(),
+                )
+                .wrap()
+            )
+            .wrap()
+        )
+        .simplify()
+    );
+}