repl: use readline

build.zig

@@ -6,6 +6,7 @@ fn setupLinks(step: *builds.LibExeObjStep) void {
 
     step.linkSystemLibrary("lilv-0");
     step.linkSystemLibrary("sndfile");
+    step.linkSystemLibrary("readline");
 
     step.linkSystemLibrary("GraphicsMagickWand");
     step.linkSystemLibrary("GraphicsMagick");

src/main.zig

@@ -8,6 +8,14 @@ test "scritcher" {
     _ = @import("runner.zig");
 }
 
+const readline = @cImport({
+    @cInclude("stdio.h");
+    @cInclude("stdlib.h");
+
+    @cInclude("readline/readline.h");
+    @cInclude("readline/history.h");
+});
+
 fn wrapInCmdList(allocator: *std.mem.Allocator, cmd: langs.Command) !langs.CommandList {
     var cmds = langs.CommandList.init(allocator);
     try cmds.append(cmd);
@@ -69,13 +77,13 @@ pub fn doRepl(allocator: *std.mem.Allocator, args_it: var) !void {
 
     while (true) {
         lang.reset();
-        try stdout.print("> ");
 
-        var buffer = try std.Buffer.init(allocator, ""[0..]);
-        var line = std.io.readLine(&buffer) catch |err| {
-            if (err == error.EndOfStream) break;
-            return err;
-        };
+        var rd_line = readline.readline(c"> ");
+        if (rd_line == null) break;
+        readline.add_history(rd_line);
+        defer std.heap.c_allocator.destroy(rd_line);
+
+        var line = rd_line[0..std.mem.len(u8, rd_line)];
 
         if (std.mem.eql(u8, line, "push")) {
             try cmds.append(current);