Merge pull request #6 from seancorfield/main

start of looking at transducers

Author: timothypratley

.gitignore

@@ -29,3 +29,6 @@ _site/
 /checkouts
 /classes
 /target
+.calva/repl.calva-repl
+.calva/mcp-server/port
+.portal/vs-code.edn

notebooks/clojure_camp/pairing.clj

@@ -0,0 +1,42 @@
+
+(ns clojure-camp.pairing)
+
+;; let's work on an algorithm together!
+
+;; this produces a lazy sequence of strings:
+(map #(str "Hello, " % "!") ["Alice" "Bob" "Charlie"])
+
+;; here's the non-lazy transducer-based version:
+(into []
+      (map #(str "Hello, " % "!"))
+      ["Alice" "Bob" "Charlie"])
+
+;; map with a single function argument produces a transducer:
+(map #(str "Hello, " % "!"))
+
+;; we can build up xforms (transformers) using the `comp` function:
+(def xf (comp (filter #(> (count %) 3))
+              (map #(str "Hello, " % "!"))))
+
+;; and now use it with `into`:
+(into []
+      xf ; Bob gets filtered out
+      ["Alice" "Bob" "Charlie"])
+
+;; "traditional" SQL-like rows of columns:
+^:kind/table
+[{:name "Alice" :age 30 :city "Wonderland"}
+ {:name "Bob" :age 25 :city "Builderland"}
+ {:name "Charlie" :age 35 :city "Chocolate Factory"}]
+
+;; more columnar format:
+^:kind/table
+{:name ["Alice" "Bob" "Charlie"]
+ :age [30 25 35]
+ :city ["Wonderland" "Builderland" "Chocolate Factory"]}
+
+;; and display it as a portal widget:
+^:kind/portal
+{:name ["Alice" "Bob" "Charlie"]
+ :age [30 25 35]
+ :city ["Wonderland" "Builderland" "Chocolate Factory"]}