From 785b43a7b6635e6fadb94e224a094e524c9e0ccd Mon Sep 17 00:00:00 2001
From: mryouse
Date: Thu, 25 May 2023 22:52:07 +0000
Subject: length on seq

---
 chunk.d    |  6 ++++++
 compiler.d | 15 +++++++++++++++
 vm.d       |  4 ++++
 3 files changed, 25 insertions(+)

diff --git a/chunk.d b/chunk.d
index 70d7b1c..47d3c73 100644
--- a/chunk.d
+++ b/chunk.d
@@ -45,6 +45,7 @@ abstract class Seq {
     SeqType type;
     abstract Value first();
     abstract Seq rest();
+    abstract int length();
 }
 
 class List : Seq {
@@ -71,6 +72,10 @@ class List : Seq {
         return ret;
     }
 
+    override int length() {
+        return to!int(this.inner.length);
+    }
+
     override string toString() {
         return format("list ('%s' + %d)", printableValue(this.inner[0]), this.inner.length - 1);
     }
@@ -108,6 +113,7 @@ enum OpCode {
 
     OP_FIRST,   // No?
     OP_REST,
+    OP_LENGTH,
 
     OP_TYPE_CHECK_NUMBER,
     OP_TYPE_CHECK_BOOLEAN,
diff --git a/compiler.d b/compiler.d
index 92711f1..66ee664 100644
--- a/compiler.d
+++ b/compiler.d
@@ -521,6 +521,18 @@ class Compiler {
         this.func.chunk.writeOp(to!ubyte(length), args[0].line);
     }
 
+    void compileLength(Form[] args) {
+        // TODO how do we identify/propagate errors?
+        if (args.length != 1) {
+            writeln("COMPILE ERROR: 'first' expects exactly one argument");
+            return;
+        }
+        ValueType vt = this.resolve(args[0], ValueType.SEQ); // TODO need a new type
+        this.func.chunk.writeOp(OpCode.OP_TYPE_CHECK_SEQ, args[0].line);
+
+        this.func.chunk.writeOp(OpCode.OP_LENGTH, args[0].line);
+    }
+
     void compileFirst(Form[] args) {
         // TODO how do we identify/propagate errors?
         if (args.length != 1) {
@@ -676,6 +688,9 @@ class Compiler {
             case "first":
                 this.compileFirst(cons.tail);
                 break;
+            case "length":
+                this.compileLength(cons.tail);
+                break;
             case "list":
                 //return compileList(cons.tail);
                 this.compileList(cons.tail);
diff --git a/vm.d b/vm.d
index 5f1d889..40877b8 100644
--- a/vm.d
+++ b/vm.d
@@ -395,6 +395,10 @@ class VM {
                     Seq seq = asSeq(this.popA());
                     this.pushA(makeSeqValue(seq.rest()));
                     break;
+                case OpCode.OP_LENGTH:
+                    Seq seq = asSeq(this.popA());
+                    this.pushA(makeNumberValue(seq.length()));
+                    break;
                 case OpCode.OP_ADD:
                     Value b = this.popA();
                     /*
-- 
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