add file reads and main prompt

src/main.zig

@@ -1,5 +1,53 @@
 const std = @import("std");
 
-pub fn main() anyerror!void {
-    std.debug.warn("All your base are belong to us.\n");
+const Allocator = std.mem.Allocator;
+
+fn run(data: []u8) void {}
+
+fn runFile(allocator: *Allocator, path: []const u8) !void {
+    var lox_file = try std.fs.File.openRead(path);
+    defer lox_file.close();
+
+    const total_bytes = try lox_file.getEndPos();
+    var slice = try allocator.alloc(u8, total_bytes);
+    _ = try lox_file.read(slice);
+
+    run(slice);
+}
+
+fn runPrompt(allocator: *Allocator) !void {
+    var stdout_file = try std.io.getStdOut();
+    const stdout = &stdout_file.outStream().stream;
+
+    while (true) {
+        try stdout.print(">");
+        var buffer = try std.Buffer.init(allocator, ""[0..]);
+
+        var line = std.io.readLine(&buffer) catch |err| {
+            if (err == error.EndOfStream) return;
+            return err;
+        };
+
+        run(line);
+    }
+}
+
+pub fn main() anyerror!void {
+    var da = std.heap.DirectAllocator.init();
+    var arena = std.heap.ArenaAllocator.init(&da.allocator);
+    var allocator = &arena.allocator;
+
+    var args_it = std.process.args();
+
+    const jorts_arg0 = try (args_it.next(allocator) orelse {
+        // if you ever reach this, tell me what is your os lmao
+        unreachable;
+    });
+
+    const lox_path = try (args_it.next(allocator) orelse {
+        try runPrompt(allocator);
+        return;
+    });
+
+    try runFile(allocator, lox_path);
 }