Finish episode 5

docs/videos.org

@@ -152,7 +152,8 @@ CLOSED: [2022-03-12 Sat 18:38]
 - How to define functions
 - vs macros
 - vs special forms
-* Episode 4 - Conditionals
+* DONE Episode 4 - Conditionals
+CLOSED: [2022-04-09 Sat 11:24]
 ** What we learned so far
 ** what is true and what's not
 ** Let & prog family
@@ -176,3 +177,136 @@ CLOSED: [2022-03-12 Sat 18:38]
 - boundp
 - More at https://www.gnu.org/software/emacs/manual/html_node/elisp/Type-Predicates.html
 ** type-of
+* Episode 5 - Lists
+** What is a list?
+- Not a primitive type
+- A linked list made out of cons cells
+
+** Cons Cells
+- A container for pairs
+- CAR
+- CDR (could-er)
+#+NAME: ep-5-cons
+#+BEGIN_SRC graphviz-dot :file /tmp/cons.svg :cmdline -Kdot -Tsvg
+digraph {
+    graph [bgcolor=transparent]
+    fontcolor="gray80"
+    node [color=gray80 shape="box", fontcolor="gray80"]
+    edge [color=gray80]
+    rankdir = "LR"
+
+    subgraph cluster_0 {
+        label="Cell"
+        color="gray80"
+
+        graph [bgcolor=transparent, fontcolor="gray80"]
+        node [color=gray80 shape="box", fontcolor="gray80"]
+        a0[label="car: 'head"]
+        b0[label="cdr: 'tail"]
+    }
+}
+#+END_SRC
+
+#+RESULTS: ep-5-cons
+[[file:/tmp/cons.svg]]
+
+#+BEGIN_SRC emacs-lisp
+  (setq x1 (cons 'head 'tail))
+  (car x1)
+  (cdr x1)
+
+  '(head . tail)
+  (cons 2 nil)
+  (cons 1 x1)
+#+END_SRC
+
+#+NAME: ep-5-list
+#+BEGIN_SRC graphviz-dot :file /tmp/list.svg :cmdline -Kdot -Tsvg
+digraph {
+    graph [bgcolor=transparent]
+    fontcolor="gray80"
+    node [color=gray80 shape="box", fontcolor="gray80"]
+    edge [color=gray80]
+    rankdir = "LR"
+
+    subgraph cluster_0 {
+        label="Cell"
+        color="gray80"
+        graph [bgcolor=transparent, fontcolor="gray80"]
+        node [color=gray80 shape="box", fontcolor="gray80"]
+        a0[label="car: 1"]
+        b0[label="cdr: "]
+    }
+    subgraph cluster_1 {
+        label="Cell"
+        color="gray80"
+        node [color=gray80 shape="box"]
+        a1[label="car: 2"]
+        b1[label="cdr: "]
+        b0 -> a1
+    }
+    subgraph cluster_2 {
+        label="Cell"
+        color="gray80"
+        node [color=gray80 shape="box"]
+        a2[label="car: 3"]
+        b2[label="cdr: nil"]
+        b1 -> a2
+    }
+}
+
+#+END_SRC
+
+#+RESULTS: ep-5-list
+[[file:/tmp/list.svg]]
+
+#+BEGIN_SRC emacs-lisp
+  (setq x2 (cons 1  (cons 2 (cons 3 nil))))
+  (setq x3 (list 1 2 3))
+#+END_SRC
+
+** Some useful functions
+- add-to-list
+#+BEGIN_SRC emacs-lisp
+  (setq x4 (list 1 2 3 4))
+  (add-to-list 'x4 3)
+  (add-to-list 'x4 6)
+#+END_SRC
+
+- push & pop
+#+BEGIN_SRC emacs-lisp
+  (setq x5 (list 1 2 3 4))
+  (push 1 x5)
+  (pop x5)
+#+END_SRC
+
+- member
+#+BEGIN_SRC emacs-lisp
+  (setq x6 (list 'a 'b 1 2))
+  (member 'z x6)
+  (member 1 x6)
+#+END_SRC
+
+- delete
+#+BEGIN_SRC emacs-lisp
+  (setq x7 (list 1 2 3 4 5))
+  (delete 3 x7)
+  x7
+#+END_SRC
+
+- remove
+#+BEGIN_SRC emacs-lisp
+  (setq x8 (list 1 2 3 4 5))
+  (remove 3 x8)
+  x8
+#+END_SRC
+
+- car
+- cdr
+#+BEGIN_SRC emacs-lisp
+  (setq  x9 (list 1 2 3 4))
+  (car x9)
+  (cdr x9)
+#+END_SRC
+
+* Episode 6 - Property & Association Lists