feat: add repl bin

.envrc

@@ -1 +1,17 @@
-use flake
+#!/usr/bin/env bash
+# ^ make editor happy
+
+#
+# Use https://direnv.net/ to automatically load the dev shell.
+#
+
+if ! has nix_direnv_version || ! nix_direnv_version 3.0.4; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.0.4/direnvrc" "sha256-DzlYZ33mWF/Gs8DDeyjr8mnVmQGx7ASYqA5WlxwvBG4="
+fi  
+
+watch_file nix/**
+watch_file -- **/*.nix
+# Adding files to git includes them in a flake
+# But it is also a bit much reloading.
+# watch_file .git/index .git/HEAD
+use flake . --show-trace

Cargo.toml

@@ -6,6 +6,14 @@ version = "0.1.0"
 
 edition = "2021"
 
+[[bin]]
+name = "demo"
+path = "src/demo.rs"
+
+[[bin]]
+name = "repl"
+path = "src/repl.rs"
+
 [dependencies]
 as-any = "0.3.1"
 futures = "0.3.30"

flake.nix

@@ -18,17 +18,20 @@
   };
 
   nixConfig = {
+    extra-trusted-public-keys = "eigenvalue.cachix.org-1:ykerQDDa55PGxU25CETy9wF6uVDpadGGXYrFNJA3TUs=";
+    extra-substituters = "https://eigenvalue.cachix.org";
     allow-import-from-derivation = true;
   };
 
-  outputs =
-    inputs @ { self
-    , nixpkgs
-    , flake-parts
-    , rust-overlay
-    , crate2nix
-    , ...
-    }: flake-parts.lib.mkFlake { inherit inputs; } {
+  outputs = inputs @ {
+    self,
+    nixpkgs,
+    flake-parts,
+    rust-overlay,
+    crate2nix,
+    ...
+  }:
+    flake-parts.lib.mkFlake {inherit inputs;} {
       systems = [
         "x86_64-linux"
         "aarch64-linux"
@@ -41,37 +44,49 @@
         ./nix/devshell/flake-module.nix
       ];
 
-      perSystem = { system, pkgs, lib, inputs', ... }:
-        let
-          # If you dislike IFD, you can also generate it with `crate2nix generate` 
-          # on each dependency change and import it here with `import ./Cargo.nix`.
-          cargoNix = inputs.crate2nix.tools.${system}.appliedCargoNix {
-            name = "rustnix";
-            src = ./.;
-          };
-        in
-        rec {
-          checks = {
-            rustnix = cargoNix.rootCrate.build.override {
-              runTests = true;
-            };
-          };
-
-          packages = rec {
-            rustnix = cargoNix.rootCrate.build;
-            default = packages.rustnix;
-            dockerImage = pkgs.dockerTools.buildImage {
-              name = "lispers";
-              config = { Cmd = [ "${rustnix}/bin/lispers" ]; };
-            };
-
-            inherit (pkgs) rust-toolchain;
-
-            rust-toolchain-versions = pkgs.writeScriptBin "rust-toolchain-versions" ''
-              ${pkgs.rust-toolchain}/bin/cargo --version
-              ${pkgs.rust-toolchain}/bin/rustc --version
-            '';
+      perSystem = {
+        system,
+        pkgs,
+        lib,
+        inputs',
+        ...
+      }: let
+        # If you dislike IFD, you can also generate it with `crate2nix generate`
+        # on each dependency change and import it here with `import ./Cargo.nix`.
+        cargoNix = inputs.crate2nix.tools.${system}.appliedCargoNix {
+          name = "rustnix";
+          src = ./.;
+        };
+      in rec {
+        checks = {
+          rustnix = cargoNix.rootCrate.build.override {
+            runTests = true;
           };
         };
+
+        apps = rec {
+          demo = {
+            type = "app";
+            program = "${packages.default}/bin/demo";
+          };
+          repl = {
+            type = "app";
+            program = "${packages.default}/bin/repl";
+          };
+          default = demo;
+        };
+
+        packages = {
+          rustnix = cargoNix.rootCrate.build;
+          default = packages.rustnix;
+
+          inherit (pkgs) rust-toolchain;
+
+          rust-toolchain-versions = pkgs.writeScriptBin "rust-toolchain-versions" ''
+            ${pkgs.rust-toolchain}/bin/cargo --version
+            ${pkgs.rust-toolchain}/bin/rustc --version
+          '';
+        };
+      };
     };
 }

src/repl.rs

@@ -0,0 +1,33 @@
+use lisp::Expression;
+use parser::ParserError;
+
+use std::io::Write;
+mod parser;
+mod lisp;
+
+fn main() {
+    let env = lisp::Environment::default();
+
+    loop {
+        print!("> ");
+        std::io::stdout().flush().unwrap();
+
+        let mut input = String::new();
+        if std::io::stdin().read_line(&mut input).unwrap() == 0 {
+            println!("Exiting REPL...");
+            break;
+        }
+
+        match parser::ExpressionStream::from_char_stream(input.chars()).collect::<Result<Vec<Expression>, ParserError>>() {
+            Err(e) => println!("Parser Error: {:?}", e),
+            Ok(exprs) => {
+                for expr in exprs {
+                    match lisp::eval(&env, expr) {
+                        Err(e) => println!("Eval Error: {}", e),
+                        Ok(val) => println!("{}", val),
+                    }
+                }
+            }
+        }
+    }
+}