From 524f03bf0837299b544ff5176e60ce375adfd69b Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sat, 30 Sep 2017 19:11:04 +0200
Subject: [PATCH 01/20] refactor map for use in a generator

---
 app.js | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/app.js b/app.js
index 54a1fb5..b28a57c 100644
--- a/app.js
+++ b/app.js
@@ -104,11 +104,22 @@
                 throw Error("At least one expression required in begin block.");
             }
             const [_, ...exps] = x;
-            return exps.map(exp => yield * evaluate(exp, env)).slice(-1)[0];
+            return exps.map(exp => evaluate(exp, env)).slice(-1)[0];
         } else {
             // Function call (no special form)
             const func_name = typeof x[0] === "string" ? x[0] : "<anon>";
-            const [func, ...args] = x.map(exp => yield * evaluate(exp, env));
+
+            // because we're yield'ing map is not allowed...
+            // 
+            // const [func, ...args] = x.map(exp => yield * evaluate(exp, env));
+            // 
+            var evald = []
+            for (var i=0; i<x.length; i++) {
+                let oneeval = yield* evaluate(x[i], env);
+                evald.push(oneeval);
+            }
+            const [func, ...args] = evald;
+
             if (typeof func === "function") {
                 // Native JavaScript function call
                 return func(...args);

From 6435f52c4701503292ce36eb9bc47e81a9705935 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sat, 30 Sep 2017 19:22:29 +0200
Subject: [PATCH 02/20] other map refactored

---
 app.js | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/app.js b/app.js
index b28a57c..d676aaa 100644
--- a/app.js
+++ b/app.js
@@ -104,7 +104,16 @@
                 throw Error("At least one expression required in begin block.");
             }
             const [_, ...exps] = x;
-            return exps.map(exp => evaluate(exp, env)).slice(-1)[0];
+
+            // because we're yield'ing map is not allowed...
+            // 
+            // return exps.map(exp => evaluate(exp, env)).slice(-1)[0];
+            // 
+            var last_evald = undefined;
+            for (var i=0; i<exps.length; i++) {
+                last_evald = yield* evaluate(exps[i], env);
+            }
+            return last_evald
         } else {
             // Function call (no special form)
             const func_name = typeof x[0] === "string" ? x[0] : "<anon>";

From d36c5be22135ee8f5a3f14b8e3a777cb5b30e312 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sat, 30 Sep 2017 22:10:43 +0200
Subject: [PATCH 03/20] very first working impl of a debugger

---
 app.js     | 64 ++++++++++++++++++++++++++++++++++++++++++------------
 index.html |  3 ++-
 2 files changed, 52 insertions(+), 15 deletions(-)

diff --git a/app.js b/app.js
index d676aaa..19f0452 100644
--- a/app.js
+++ b/app.js
@@ -98,6 +98,8 @@
             }
             return env[x];
         } else if (x instanceof Number) {
+            x.doing = true;
+            yield x;
             return x.valueOf();
         } else if (x[0].valueOf() === "begin") {
             if (x.length < 2) {
@@ -201,7 +203,8 @@
             global_env: global_env,
             result: undefined,
             error: false,
-            debug: true
+            debug: true,
+            eval_gen: undefined,
         },
         computed: {
             parenBalance: function() {
@@ -209,6 +212,33 @@
                        this.input.split(")").length;
             }
         },
+        methods: {
+            step: function() {
+                this.result = undefined;
+                var {value: result, done} = this.eval_gen.next();
+
+                // tell vue to update token list
+                let token_idx = this.tokens.findIndex(el => el.id == result.id);
+                Vue.set(this.tokens, token_idx, result);
+                if (!done) {
+                    return result;
+                }
+
+                // we're done stepping: reset eval_gen to null
+                this.eval_gen = null;
+
+                // return final result
+                if (result instanceof Array) {
+                    const pprint = tree => tree instanceof Array ?
+                        "(" + tree.map(pprint).join(" ") + ")" : tree;
+                    this.result = pprint(result.slice(0, -1));
+                } else if (typeof result === "function") {
+                    this.result = "native function: " + result.name;
+                } else {
+                    this.result = result;
+                }
+            }
+        },
         watch: {
             input: function(val) {
                 this.ast = [];
@@ -219,20 +249,26 @@
                     this.ast = parse(this.tokens.slice());
                     this.env = Object.create(this.global_env);
 
-                    let evaluate_gen = evaluate(this.ast, this.env);
-                    while (!done) {
-                        var {value: result, done} = evaluate_gen.next();
-                    }
+                    // let evaluate_gen = evaluate(this.ast, this.env);
+                    // while (!done) {
+                    //     var {value: result, done} = evaluate_gen.next();
+                    //     console.log(result);
+                    // }
+                    this.eval_gen = evaluate(this.ast, this.env);
+                    // while (!done) {
+                    //     var {value: result, done} = evaluate_gen.next();
+                    //     console.log(result);
+                    // }
 
-                    if (result instanceof Array) {
-                        const pprint = tree => tree instanceof Array ?
-                            "(" + tree.map(pprint).join(" ") + ")" : tree;
-                        this.result = pprint(result.slice(0, -1));
-                    } else if (typeof result === "function") {
-                        this.result = "native function: " + result.name;
-                    } else {
-                        this.result = result;
-                    }
+                    // if (result instanceof Array) {
+                    //     const pprint = tree => tree instanceof Array ?
+                    //         "(" + tree.map(pprint).join(" ") + ")" : tree;
+                    //     this.result = pprint(result.slice(0, -1));
+                    // } else if (typeof result === "function") {
+                    //     this.result = "native function: " + result.name;
+                    // } else {
+                    //     this.result = result;
+                    // }
                 } catch (error) {
                     this.error = error;
                 }
diff --git a/index.html b/index.html
index 94f3043..73cfb7d 100644
--- a/index.html
+++ b/index.html
@@ -17,8 +17,9 @@ <h4>Source</h4>
       <code class="chrome">)</code>
       <p v-if="error" class="error"><strong>{{error.name}}: </strong>{{error.message}}</p>
       <template v-else>
+
         <h4>Step</h4>
-        <p class="code"><button>Step</button></p>
+        <p v-if="eval_gen" class="code"><button v-on:click="step">Step</button></p>
         <h4>Result</h4>
         <p class="code">{{result}}</p>
       </template>

From 22be3a5fbf88678b908e802bb870b558271c382a Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sat, 30 Sep 2017 22:23:22 +0200
Subject: [PATCH 04/20] mark the function aswell

---
 app.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/app.js b/app.js
index 19f0452..4c89103 100644
--- a/app.js
+++ b/app.js
@@ -96,6 +96,8 @@
             if (typeof res === "undefined") {
                 throw Error("Variable '" + x + "' not found");
             }
+            x.doing = true;
+            yield x;
             return env[x];
         } else if (x instanceof Number) {
             x.doing = true;
@@ -277,7 +279,7 @@
     });
 
     // Example input:
-    vm.input = `(+ 2 2)`;
+    vm.input = `(+ (+ 2 2) 5)`;
 
     vm.input_ = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
 (define avg  (lambda (a b) (/ (+ a b) 2) ))

From ef9f5451480d105f6d40869f3ad1f9799a7291da Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sat, 30 Sep 2017 22:24:21 +0200
Subject: [PATCH 05/20] cleanup

---
 app.js | 19 -------------------
 1 file changed, 19 deletions(-)

diff --git a/app.js b/app.js
index 4c89103..db85c39 100644
--- a/app.js
+++ b/app.js
@@ -251,26 +251,7 @@
                     this.ast = parse(this.tokens.slice());
                     this.env = Object.create(this.global_env);
 
-                    // let evaluate_gen = evaluate(this.ast, this.env);
-                    // while (!done) {
-                    //     var {value: result, done} = evaluate_gen.next();
-                    //     console.log(result);
-                    // }
                     this.eval_gen = evaluate(this.ast, this.env);
-                    // while (!done) {
-                    //     var {value: result, done} = evaluate_gen.next();
-                    //     console.log(result);
-                    // }
-
-                    // if (result instanceof Array) {
-                    //     const pprint = tree => tree instanceof Array ?
-                    //         "(" + tree.map(pprint).join(" ") + ")" : tree;
-                    //     this.result = pprint(result.slice(0, -1));
-                    // } else if (typeof result === "function") {
-                    //     this.result = "native function: " + result.name;
-                    // } else {
-                    //     this.result = result;
-                    // }
                 } catch (error) {
                     this.error = error;
                 }

From 9f48482c3c66fe2861f52445b7b2187ee1cb9a8e Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sat, 30 Sep 2017 23:09:31 +0200
Subject: [PATCH 06/20] start and finish function call

---
 app.js     | 32 ++++++++++++++++++++++++--------
 index.html |  2 +-
 styles.css |  8 ++++++++
 3 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/app.js b/app.js
index db85c39..24552a0 100644
--- a/app.js
+++ b/app.js
@@ -96,7 +96,7 @@
             if (typeof res === "undefined") {
                 throw Error("Variable '" + x + "' not found");
             }
-            x.doing = true;
+            x.started = true;
             yield x;
             return env[x];
         } else if (x instanceof Number) {
@@ -127,15 +127,23 @@
             // const [func, ...args] = x.map(exp => yield * evaluate(exp, env));
             // 
             var evald = []
+            var first_tok, last_tok;
             for (var i=0; i<x.length; i++) {
                 let oneeval = yield* evaluate(x[i], env);
                 evald.push(oneeval);
+                first_tok = x[0];
+                last_tok = x[x.length-1];
             }
             const [func, ...args] = evald;
 
             if (typeof func === "function") {
                 // Native JavaScript function call
-                return func(...args);
+                let func_result = func(...args);
+                first_tok.started = false;
+                first_tok.doing = true;
+                yield first_tok;
+
+                return func_result;
             } else if (func instanceof Array) {
                 // MiniScheme function call
                 const [_, arg_names, body, definition_env] = func;
@@ -217,13 +225,21 @@
         methods: {
             step: function() {
                 this.result = undefined;
-                var {value: result, done} = this.eval_gen.next();
 
-                // tell vue to update token list
-                let token_idx = this.tokens.findIndex(el => el.id == result.id);
-                Vue.set(this.tokens, token_idx, result);
-                if (!done) {
-                    return result;
+                if (true) {
+                    var {value: result, done} = this.eval_gen.next();
+                    
+                    // tell vue to update token list
+                    let token_idx = this.tokens.findIndex(el => el.id == result.id);
+                    Vue.set(this.tokens, token_idx, result);
+                    if (!done) {
+                        return result;
+                    }
+                } else {
+                    while (!done) {
+                        var {value: result, done} = this.eval_gen.next();
+                        console.log(result);
+                    }
                 }
 
                 // we're done stepping: reset eval_gen to null
diff --git a/index.html b/index.html
index 73cfb7d..81cd053 100644
--- a/index.html
+++ b/index.html
@@ -27,7 +27,7 @@ <h4>Result</h4>
         <h4>Tokens</h4>
         <p>
           <template v-for="token in tokens">
-            <span v-bind:id="token.id" class="token tooltip" v-bind:class="{tokendone: token.doing}" :key="token.valueOf()">
+            <span v-bind:id="token.id" class="token tooltip" v-bind:class="{tokendone: token.doing, tokenstarted: token.started}" :key="token.valueOf()">
               {{token.valueOf()}}<span class="tooltiptext">Line: {{token.line}}:{{token.col}}</span></span>&nbsp;
           </template>
         </p>
diff --git a/styles.css b/styles.css
index 20ab5d8..ce79225 100644
--- a/styles.css
+++ b/styles.css
@@ -76,6 +76,14 @@ span.tokendone {
   line-height: 2.2;
 }
 
+span.tokenstarted {
+  border: 2px darkblue solid;
+  background-color: #B2E6AD;
+  padding: 2px 5px;
+  border-radius: 4px;
+  line-height: 2.2;
+}
+
 ul.env {
   display: inline-block;
   list-style: none;

From 4eac6a82f98c1457d4c8de419666dc150af16bb6 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sat, 30 Sep 2017 23:10:50 +0200
Subject: [PATCH 07/20] hide step label

---
 index.html | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/index.html b/index.html
index 81cd053..fc729fc 100644
--- a/index.html
+++ b/index.html
@@ -18,7 +18,7 @@ <h4>Source</h4>
       <p v-if="error" class="error"><strong>{{error.name}}: </strong>{{error.message}}</p>
       <template v-else>
 
-        <h4>Step</h4>
+        <h4 v-if="eval_gen">Step</h4>
         <p v-if="eval_gen" class="code"><button v-on:click="step">Step</button></p>
         <h4>Result</h4>
         <p class="code">{{result}}</p>

From 6f6f83387e4142a643d3a602f1841bfa3fa089bb Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 12:40:17 +0200
Subject: [PATCH 08/20] implemented debugger step and continue

---
 app.js     | 34 ++++++++++++++++++----------------
 index.html | 10 ++++++----
 2 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/app.js b/app.js
index 24552a0..cd2fe95 100644
--- a/app.js
+++ b/app.js
@@ -223,28 +223,30 @@
             }
         },
         methods: {
-            step: function() {
-                this.result = undefined;
+            debuggerStep: function() {
+                var {value: result, done} = this.eval_gen.next();
+                
+                // tell vue to update token list
+                let token_idx = this.tokens.findIndex(el => el.id == result.id);
+                Vue.set(this.tokens, token_idx, result);
+                if (!done) {
+                    return result;
+                }
 
-                if (true) {
+                // we're done stepping: reset eval_gen to null
+                this.eval_gen = null;
+                this.processResult(result);
+            },
+            debuggerContinue: function() {
+                while (!done) {
                     var {value: result, done} = this.eval_gen.next();
-                    
-                    // tell vue to update token list
-                    let token_idx = this.tokens.findIndex(el => el.id == result.id);
-                    Vue.set(this.tokens, token_idx, result);
-                    if (!done) {
-                        return result;
-                    }
-                } else {
-                    while (!done) {
-                        var {value: result, done} = this.eval_gen.next();
-                        console.log(result);
-                    }
                 }
 
                 // we're done stepping: reset eval_gen to null
                 this.eval_gen = null;
-
+                this.processResult(result);
+            },
+            processResult: function(result) {
                 // return final result
                 if (result instanceof Array) {
                     const pprint = tree => tree instanceof Array ?
diff --git a/index.html b/index.html
index fc729fc..73058bf 100644
--- a/index.html
+++ b/index.html
@@ -17,11 +17,13 @@ <h4>Source</h4>
       <code class="chrome">)</code>
       <p v-if="error" class="error"><strong>{{error.name}}: </strong>{{error.message}}</p>
       <template v-else>
-
         <h4 v-if="eval_gen">Step</h4>
-        <p v-if="eval_gen" class="code"><button v-on:click="step">Step</button></p>
-        <h4>Result</h4>
-        <p class="code">{{result}}</p>
+        <p v-if="eval_gen" class="code">
+          <button v-on:click="debuggerStep">Step</button>
+          <button v-on:click="debuggerContinue">Continue</button>
+        </p>
+        <h4 v-if="!eval_gen">Result</h4>
+        <p v-if="!eval_gen" class="code">{{result}}</p>
       </template>
       <div class="tokens">
         <h4>Tokens</h4>

From c3856918ff73aafdacf53a96cb0a7cd3c8b6942c Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 12:43:25 +0200
Subject: [PATCH 09/20] generator function playground

---
 recu.js | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 recu.js

diff --git a/recu.js b/recu.js
new file mode 100644
index 0000000..893a436
--- /dev/null
+++ b/recu.js
@@ -0,0 +1,16 @@
+
+// this is a small function to play with and demonstrate the use of generator functions
+
+
+function* recu(level, currval) {
+	if (currval < 3) {
+		console.log('hello: ' + currval + ' level: ' + level);
+		currval += 1;
+		final = yield* recu(level+1, currval);
+	} else {
+		console.log('returning from level: ' + level + ' with currval: ' + currval);
+		return currval;
+	}
+	debugger;
+	return final;
+}
\ No newline at end of file

From 57a3b9ce2f9ad5b7de59580181a702edf933fc7c Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 15:22:52 +0200
Subject: [PATCH 10/20] put functs back where they belong

---
 app.js | 40 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/app.js b/app.js
index cd2fe95..9e5d43d 100644
--- a/app.js
+++ b/app.js
@@ -103,6 +103,27 @@
             x.doing = true;
             yield x;
             return x.valueOf();
+        } else if (x[0].valueOf() === "if") {
+            if (x.length != 4) {
+                throw Error("Wrong number of arguments for if: " +
+                    (x.length - 1) + " != 3");
+            }
+            const [_, test, conseq, alt] = x;
+            const exp = (yield* evaluate(test, env)) ? conseq : alt;
+            yield* evaluate(exp, env);
+        } else if (x[0].valueOf() === "define") {
+            if (x.length != 3) {
+                throw Error("Wrong number of arguments for define: " +
+                    (x.length - 1) + " != 2");
+            }
+            const [_, name, exp] = x;
+            if (!(name instanceof String)){
+                throw Error("Name of a definition is not a string: " +
+                    typeof name);
+            } else if ("begin define if lambda".split(" ").includes(name)) {
+                throw Error("Invalid name of a definition: " + name);
+            }
+            env[name.valueOf()] = yield* evaluate(exp, env);
         } else if (x[0].valueOf() === "begin") {
             if (x.length < 2) {
                 throw Error("At least one expression required in begin block.");
@@ -118,6 +139,18 @@
                 last_evald = yield* evaluate(exps[i], env);
             }
             return last_evald
+        } else if (x[0].valueOf() === "lambda") {
+            if (x.length != 3) {
+                throw Error("Wrong number of arguments for lambda: " +
+                    (x.length - 1) + " != 2");
+            }
+            const [_, arg_names, body] = x;
+            if (!(arg_names instanceof Array)) {
+                throw Error("Function arguments must be a list");
+            }
+            // Do nothing for now, except store the current environment
+            // together with the function definition.
+            return ["lambda", arg_names, body, env];
         } else {
             // Function call (no special form)
             const func_name = typeof x[0] === "string" ? x[0] : "<anon>";
@@ -278,7 +311,12 @@
     });
 
     // Example input:
-    vm.input = `(+ (+ 2 2) 5)`;
+    vm.input =  `(if (< 2 3) 2 3)`;
+
+vm.input_ =  `(define x 3)
+    (+ (+ 2 2) x)`;
+        
+    vm.input_ = `(+ (+ 2 2) 5)`;
 
     vm.input_ = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
 (define avg  (lambda (a b) (/ (+ a b) 2) ))

From 951612caef36bdb4d2d0db47c84d763ef0e8361e Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 16:12:13 +0200
Subject: [PATCH 11/20] if now works

---
 app.js | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/app.js b/app.js
index 9e5d43d..09330d3 100644
--- a/app.js
+++ b/app.js
@@ -110,7 +110,8 @@
             }
             const [_, test, conseq, alt] = x;
             const exp = (yield* evaluate(test, env)) ? conseq : alt;
-            yield* evaluate(exp, env);
+            var last_evald = yield* evaluate(exp, env);
+            return last_evald;
         } else if (x[0].valueOf() === "define") {
             if (x.length != 3) {
                 throw Error("Wrong number of arguments for define: " +
@@ -134,7 +135,7 @@
             // 
             // return exps.map(exp => evaluate(exp, env)).slice(-1)[0];
             // 
-            var last_evald = undefined;
+            var last_evald;
             for (var i=0; i<exps.length; i++) {
                 last_evald = yield* evaluate(exps[i], env);
             }
@@ -311,10 +312,15 @@
     });
 
     // Example input:
-    vm.input =  `(if (< 2 3) 2 3)`;
+    vm.input =  `(define avg  (lambda (a b) (/ (+ a b) 2) ))
+(avg 6 12)`;
 
-vm.input_ =  `(define x 3)
-    (+ (+ 2 2) x)`;
+    vm.input_ =  `(define avg  (lambda (a b) (/ (+ a b) 2) ))
+(if (< 2 3) 2 3)
+`;
+    
+    vm.input_ =  `(define x 3)
+(+ (+ 2 2) x)`;
         
     vm.input_ = `(+ (+ 2 2) 5)`;
 

From 545dd590c5ca39b856e09639055a60ce79b519d1 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 16:22:40 +0200
Subject: [PATCH 12/20] sqrt works now

---
 app.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/app.js b/app.js
index 09330d3..080c674 100644
--- a/app.js
+++ b/app.js
@@ -196,7 +196,8 @@
                 }, Object.create(definition_env));
 
                 // Evaluate the function body with the newly created environment
-                return evaluate(body, call_env);
+                var last_evald = yield* evaluate(body, call_env);
+                return last_evald;
             }
         }
     }
@@ -322,7 +323,7 @@
     vm.input_ =  `(define x 3)
 (+ (+ 2 2) x)`;
         
-    vm.input_ = `(+ (+ 2 2) 5)`;
+    vm.input = `(+ (+ 2 2) 5)`;
 
     vm.input_ = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
 (define avg  (lambda (a b) (/ (+ a b) 2) ))

From a240d20e59aad16ac5943c22799eeb11c1379531 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 16:36:07 +0200
Subject: [PATCH 13/20] rename doing => done

---
 app.js     | 10 ++++------
 index.html |  4 ++--
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/app.js b/app.js
index 080c674..3a5880b 100644
--- a/app.js
+++ b/app.js
@@ -100,7 +100,7 @@
             yield x;
             return env[x];
         } else if (x instanceof Number) {
-            x.doing = true;
+            x.done = true;
             yield x;
             return x.valueOf();
         } else if (x[0].valueOf() === "if") {
@@ -174,7 +174,7 @@
                 // Native JavaScript function call
                 let func_result = func(...args);
                 first_tok.started = false;
-                first_tok.doing = true;
+                first_tok.done = true;
                 yield first_tok;
 
                 return func_result;
@@ -316,14 +316,12 @@
     vm.input =  `(define avg  (lambda (a b) (/ (+ a b) 2) ))
 (avg 6 12)`;
 
-    vm.input_ =  `(define avg  (lambda (a b) (/ (+ a b) 2) ))
-(if (< 2 3) 2 3)
-`;
+    vm.input_ =  `(if (< 2 3) 2 3)`;
     
     vm.input_ =  `(define x 3)
 (+ (+ 2 2) x)`;
         
-    vm.input = `(+ (+ 2 2) 5)`;
+    vm.input_ = `(+ (+ 2 2) 5)`;
 
     vm.input_ = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
 (define avg  (lambda (a b) (/ (+ a b) 2) ))
diff --git a/index.html b/index.html
index 73058bf..325e697 100644
--- a/index.html
+++ b/index.html
@@ -17,7 +17,7 @@ <h4>Source</h4>
       <code class="chrome">)</code>
       <p v-if="error" class="error"><strong>{{error.name}}: </strong>{{error.message}}</p>
       <template v-else>
-        <h4 v-if="eval_gen">Step</h4>
+        <h4 v-if="eval_gen">Debugger</h4>
         <p v-if="eval_gen" class="code">
           <button v-on:click="debuggerStep">Step</button>
           <button v-on:click="debuggerContinue">Continue</button>
@@ -29,7 +29,7 @@ <h4 v-if="!eval_gen">Result</h4>
         <h4>Tokens</h4>
         <p>
           <template v-for="token in tokens">
-            <span v-bind:id="token.id" class="token tooltip" v-bind:class="{tokendone: token.doing, tokenstarted: token.started}" :key="token.valueOf()">
+            <span v-bind:id="token.id" class="token tooltip" v-bind:class="{tokendone: token.done, tokenstarted: token.started}" :key="token.valueOf()">
               {{token.valueOf()}}<span class="tooltiptext">Line: {{token.line}}:{{token.col}}</span></span>&nbsp;
           </template>
         </p>

From 32710dc47536a71061a8508772cb4c1695d75a93 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 22:40:37 +0200
Subject: [PATCH 14/20] mark started and done elements

---
 app.js | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/app.js b/app.js
index 3a5880b..bdb04c6 100644
--- a/app.js
+++ b/app.js
@@ -90,18 +90,31 @@
         "<=": (a, b) => a <= b,
     };
 
+    function* markStarted(node) {
+        node.started = true;
+        yield node;
+    }
+
+    function* markDone(node) {
+        node.started = false;
+        node.done = true;
+        yield node;
+    }
+
     function* evaluate(x, env) {
         if (x instanceof String) {
             const res = env[x.valueOf()];
             if (typeof res === "undefined") {
                 throw Error("Variable '" + x + "' not found");
             }
-            x.started = true;
-            yield x;
-            return env[x];
+            yield* markStarted(x);
+            var fromEnv = env[x];
+            if (!Array.isArray(fromEnv) && typeof fromEnv !== "function") {
+                yield* markDone(x);
+            }
+            return fromEnv;
         } else if (x instanceof Number) {
-            x.done = true;
-            yield x;
+            yield* markDone(x);
             return x.valueOf();
         } else if (x[0].valueOf() === "if") {
             if (x.length != 4) {
@@ -124,7 +137,11 @@
             } else if ("begin define if lambda".split(" ").includes(name)) {
                 throw Error("Invalid name of a definition: " + name);
             }
+            yield* markStarted(_);
+            yield* markStarted(name);
             env[name.valueOf()] = yield* evaluate(exp, env);
+            yield* markDone(name);
+            yield* markDone(_);
         } else if (x[0].valueOf() === "begin") {
             if (x.length < 2) {
                 throw Error("At least one expression required in begin block.");
@@ -151,6 +168,8 @@
             }
             // Do nothing for now, except store the current environment
             // together with the function definition.
+            yield* markStarted(x[0]);
+            yield* markDone(x[0]);
             return ["lambda", arg_names, body, env];
         } else {
             // Function call (no special form)
@@ -161,21 +180,19 @@
             // const [func, ...args] = x.map(exp => yield * evaluate(exp, env));
             // 
             var evald = []
-            var first_tok, last_tok;
+            var firstToken, lastToken;
             for (var i=0; i<x.length; i++) {
                 let oneeval = yield* evaluate(x[i], env);
                 evald.push(oneeval);
-                first_tok = x[0];
-                last_tok = x[x.length-1];
+                firstToken = x[0];
+                lastToken = x[x.length-1];
             }
             const [func, ...args] = evald;
 
             if (typeof func === "function") {
                 // Native JavaScript function call
                 let func_result = func(...args);
-                first_tok.started = false;
-                first_tok.done = true;
-                yield first_tok;
+                yield* markDone(firstToken);
 
                 return func_result;
             } else if (func instanceof Array) {
@@ -197,6 +214,7 @@
 
                 // Evaluate the function body with the newly created environment
                 var last_evald = yield* evaluate(body, call_env);
+                yield* markDone(firstToken);
                 return last_evald;
             }
         }

From 058a2d9348d740b8adafbf03123c9796286f624b Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 22:46:25 +0200
Subject: [PATCH 15/20] add examples

---
 app.js | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/app.js b/app.js
index bdb04c6..48db5d0 100644
--- a/app.js
+++ b/app.js
@@ -331,17 +331,21 @@
     });
 
     // Example input:
-    vm.input =  `(define avg  (lambda (a b) (/ (+ a b) 2) ))
+    vm.input_ =  `(define avg  (lambda (a b) (/ (+ a b) 2) ))
 (avg 6 12)`;
 
     vm.input_ =  `(if (< 2 3) 2 3)`;
-    
+
+    vm.input_ =  `(define x 4)
+(define avg  (lambda (a b) (/ (+ a b) 2) ))
+(if (< 2 3) (avg x (avg 5 10)) 3)`;
+
     vm.input_ =  `(define x 3)
 (+ (+ 2 2) x)`;
         
     vm.input_ = `(+ (+ 2 2) 5)`;
 
-    vm.input_ = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
+    vm.input = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
 (define avg  (lambda (a b) (/ (+ a b) 2) ))
 (define sqrt (lambda (x) (begin
     (define start_guess 1)

From 564281cf21ea1d2382cfa92f1bea1ed9c4f9fcb9 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 22:51:49 +0200
Subject: [PATCH 16/20] err condition check

---
 app.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/app.js b/app.js
index 48db5d0..4ed45b3 100644
--- a/app.js
+++ b/app.js
@@ -216,6 +216,12 @@
                 var last_evald = yield* evaluate(body, call_env);
                 yield* markDone(firstToken);
                 return last_evald;
+            } else {
+                if (typeof func === "undefined") {
+                    throw Error("No function supplied.");
+                } else {
+                    throw Error("Invalid function: " + func_name);
+                }
             }
         }
     }

From 4ac23ae502f41610b5f35c1f6a15be6fe869bc59 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Sun, 1 Oct 2017 23:01:41 +0200
Subject: [PATCH 17/20] mark args

---
 app.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/app.js b/app.js
index 4ed45b3..c3273a4 100644
--- a/app.js
+++ b/app.js
@@ -169,6 +169,9 @@
             // Do nothing for now, except store the current environment
             // together with the function definition.
             yield* markStarted(x[0]);
+            for (var i=0; i<arg_names.length; i++) {
+                yield* markDone(arg_names[i]);
+            }                
             yield* markDone(x[0]);
             return ["lambda", arg_names, body, env];
         } else {
@@ -342,7 +345,7 @@
 
     vm.input_ =  `(if (< 2 3) 2 3)`;
 
-    vm.input_ =  `(define x 4)
+    vm.input =  `(define x 4)
 (define avg  (lambda (a b) (/ (+ a b) 2) ))
 (if (< 2 3) (avg x (avg 5 10)) 3)`;
 
@@ -351,7 +354,7 @@
         
     vm.input_ = `(+ (+ 2 2) 5)`;
 
-    vm.input = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
+    vm.input_ = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
 (define avg  (lambda (a b) (/ (+ a b) 2) ))
 (define sqrt (lambda (x) (begin
     (define start_guess 1)

From 78f5824273df8ef71ab1f7e89714669e6e85f2c6 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Wed, 4 Oct 2017 10:34:25 +0200
Subject: [PATCH 18/20] added debugger play

---
 app.js     | 23 ++++++++++++++++++++---
 index.html |  1 +
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/app.js b/app.js
index c3273a4..a22d860 100644
--- a/app.js
+++ b/app.js
@@ -95,7 +95,8 @@
         yield node;
     }
 
-    function* markDone(node) {
+    function* markDone(node, result) {
+        node.result = result;
         node.started = false;
         node.done = true;
         yield node;
@@ -195,7 +196,7 @@
             if (typeof func === "function") {
                 // Native JavaScript function call
                 let func_result = func(...args);
-                yield* markDone(firstToken);
+                yield* markDone(firstToken, func_result);
 
                 return func_result;
             } else if (func instanceof Array) {
@@ -299,9 +300,25 @@
                 this.eval_gen = null;
                 this.processResult(result);
             },
+            debuggerPlay: function() {
+                var {value: result, done} = this.eval_gen.next();
+                
+                // tell vue to update token list
+                let token_idx = this.tokens.findIndex(el => el.id == result.id);
+                Vue.set(this.tokens, token_idx, result);
+                if (!done) {
+                    setTimeout(this.debuggerPlay, 100);
+                    return result;
+                }
+
+                // we're done stepping: reset eval_gen to null
+                this.eval_gen = null;
+                this.processResult(result);
+            },
             debuggerContinue: function() {
                 while (!done) {
                     var {value: result, done} = this.eval_gen.next();
+                    
                 }
 
                 // we're done stepping: reset eval_gen to null
@@ -354,7 +371,7 @@
         
     vm.input_ = `(+ (+ 2 2) 5)`;
 
-    vm.input_ = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
+    vm.input = `(define abs  (lambda (a) (if (> a 0) a (- 0 a))))
 (define avg  (lambda (a b) (/ (+ a b) 2) ))
 (define sqrt (lambda (x) (begin
     (define start_guess 1)
diff --git a/index.html b/index.html
index 325e697..251a23b 100644
--- a/index.html
+++ b/index.html
@@ -21,6 +21,7 @@ <h4 v-if="eval_gen">Debugger</h4>
         <p v-if="eval_gen" class="code">
           <button v-on:click="debuggerStep">Step</button>
           <button v-on:click="debuggerContinue">Continue</button>
+          <button v-on:click="debuggerPlay">Play</button>
         </p>
         <h4 v-if="!eval_gen">Result</h4>
         <p v-if="!eval_gen" class="code">{{result}}</p>

From 58df7d6fd45eb7cd1a67f60f3d051848cd20c706 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Mon, 9 Oct 2017 10:50:29 +0200
Subject: [PATCH 19/20] no message

---
 app.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app.js b/app.js
index a22d860..35430cc 100644
--- a/app.js
+++ b/app.js
@@ -307,7 +307,7 @@
                 let token_idx = this.tokens.findIndex(el => el.id == result.id);
                 Vue.set(this.tokens, token_idx, result);
                 if (!done) {
-                    setTimeout(this.debuggerPlay, 100);
+                    setTimeout(this.debuggerPlay, 80);
                     return result;
                 }
 

From d6ad348c78b3f185b7573cf9ec2c3cf0fa6ff919 Mon Sep 17 00:00:00 2001
From: Pawel Kowalski <pawel.kowalski@iterativ.ch>
Date: Tue, 10 Oct 2017 10:27:08 +0200
Subject: [PATCH 20/20] added logrocket

---
 app.js     | 2 +-
 index.html | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/app.js b/app.js
index 35430cc..3cc46a7 100644
--- a/app.js
+++ b/app.js
@@ -288,7 +288,7 @@
         methods: {
             debuggerStep: function() {
                 var {value: result, done} = this.eval_gen.next();
-                
+
                 // tell vue to update token list
                 let token_idx = this.tokens.findIndex(el => el.id == result.id);
                 Vue.set(this.tokens, token_idx, result);
diff --git a/index.html b/index.html
index 251a23b..4d78982 100644
--- a/index.html
+++ b/index.html
@@ -4,6 +4,8 @@
     <meta charset="utf-8">
     <title>mini-scheme.js</title>
     <link rel="stylesheet" href="styles.css">
+    <script src="https://cdn.logrocket.com/LogRocket.min.js"></script>
+    <script>window.LogRocket && window.LogRocket.init('cf4wag/mini-scheme');</script>
   </head>
   <body>
     <h1>mini-scheme.js</h1>