second commit

src/clj/transducerpres/slides/what.clj

@@ -1,15 +1,79 @@
 (ns transducerpres.slides.what
-    (:require [transducerpres.slides.util :refer [defslide]]))
+    (:require [transducerpres.slides.util :refer [defslide defmarkdownslide clj-code markdown-slide markdown-part]]))
 
 (defslide title
     [:h3 "What is a Transducer?"])
 
-(defslide wikipedia-definition
-    [:h4 "According to Wikipedia"]
-    [:cite "A transducer is a device that converts one form of energy to another"]
-    [:cite "..."]
-    [:cite "Transducers are often employed at the boundaries of automation"])
+(defmarkdownslide wikipedia-definition
+    "#### According to Wikipedia"
+    "> A **transducer** is a device that converts one form of energy to another"
+    "> ..."
+    ">Transducers are often employed at the boundaries...")
+
+(defmarkdownslide clojuredoc-definition
+    "#### According to clojuredoc"
+    "A **transducer** (sometimes referred to as **xform** or **xf**) is a "
+    "transformation from one reducing function to another")
+
+(defmarkdownslide does-not-help-much
+    "#### That does not help much"
+    "Instead let take a look at what transducer try to solve")
+
+(defslide classical-problem
+    (markdown-part
+        "#### Classical problem: $ \\sum_{n=0}^{N-1} 2 \\cdot n + 3 $")
+    (clj-code
+        "(defn classic-sum [N]"
+        "    (let [all-numbers (range)"
+        "          input (take N all-numbers)"
+        "          times-two (map #(* 2 %) input)"
+        "          times-two-plus-three (map #(+ 3 %) times-two)]"
+        "        (reduce + 0 times-two-plus-three)))")
+    (markdown-part
+        "node: Here we produce two lists when we actually do not need any"))
+
+(defslide classical-problem-with-channel
+    (markdown-part
+        "#### And the solution to a very similar problem requires a re-written")
+    (clj-code
+        "(require '[clojure.core.async :as async])")
+    (clj-code
+        "(defn classic-sum-channel [N]"
+        "    (let [all-numbers (async/to-chan (range))"
+        "          input (async/take N all-numbers)"
+        "          times-two  (async/map< #(* 2 %) input)"
+        "          times-two-plus-three  (async/map< #(+ 3 %) times-two)]"
+        "    (async/reduce + 0 times-two-plus-three)))"
+        ))
+
+(defslide classical-problem-with-transducer
+    (markdown-part
+        "#### Transducers simplify all the above fiddling")
+    (clj-code
+        "(require '[clojure.core.async :as async])")
+    (clj-code
+        "(defn xform [N]         ;; transducers are usually named xform or xf"
+        "   (comp (take N)"
+        "         (map #(* 2 %))"
+        "         (map #(+ 3 %))))"
+        ""
+        "(defn trans-classic-sum [N]"
+        "    (transduce (xform N) + 0 (range)))"
+        ""
+        "(defn trans-classic-sum-channel [N]"
+        "    (async/transduce (xform N) + 0 (async/to-chan (range))))"
+        ))
+
+(defmarkdownslide transducer-formal-definition
+    "Hence a **transducer** is a data pipeline \"functional interface\""
+    "that is un aware of the underlying data structure.")
 
 (defslide what-is-a-tranducer
         title
-        wikipedia-definition)
+        wikipedia-definition
+        clojuredoc-definition
+        does-not-help-much
+        classical-problem
+        classical-problem-with-channel
+        classical-problem-with-transducer
+        transducer-formal-definition)