Monads/Writer monad: Difference between revisions

Content added Content deleted

Inline

@@ Line 10: / Line 10: @@
 # Derive Writer monad versions of each of these functions
 # Apply a composition of the Writer versions of root, addOne, and half to the integer 5, deriving both a value for the Golden Ratio φ, and a concatenated log of the function applications (starting with the initial value, and followed by the application of root, etc.)
 =={{header|ALGOL 68}}==
@@ Line 722: / Line 721: @@
 added one: 2.236068 -> 3.236068
 halved it: 3.236068 -> 1.618034
-</pre>
-=={{header|zkl}}==
-{{trans|EchoLisp}}
-<lang zkl>class Writer{
-   fcn init(x){ var X=x, logText=Data(Void,"  init \U2192; ",x.toString()) }
-   fcn unit(text)  { logText.append(text); self }
-   fcn lift(f,name){ unit("\n  %s \U2192; %s".fmt(name,X=f(X))) }
-   fcn bind(f,name){ lift.fp(f,name) }
-   fcn toString{ "Result = %s\n%s".fmt(X,logText.text) }
-   fcn root{ lift(fcn(x){ x.sqrt() },"root") }
-   fcn half{ lift('/(2),"half") }
-   fcn inc { lift('+(1),"inc") }
-}</lang>
-<lang zkl>Writer(5.0).root().inc().half().println();</lang>
-{{out}}
-<pre>
-Result = 1.61803
-  init → 5
-  root → 2.23607
-  inc → 3.23607
-  half → 1.61803
-</pre>
-<lang zkl>w:=Writer(5.0);
-Utils.Helpers.fcomp(w.half,w.inc,w.root)(w).println();  // half(inc(root(w)))</lang>
-{{out}}
-<pre>
-Result = 1.61803
-  init → 5
-  root → 2.23607
-  inc → 3.23607
-  half → 1.61803
-</pre>
-Use bind to add functions to an existing Writer:
-<lang zkl>w:=Writer(5.0);
-root,inc,half := w.bind(fcn(x){ x.sqrt() },"root"), w.bind('+(1),"+ 1"), w.bind('/(2),"/ 2");
-root(); inc(); half(); w.println();</lang>
-{{out}}
-<pre>
-Result = 1.61803
-  init → 5
-  root → 2.23607
-  + 1 → 3.23607
-  / 2 → 1.61803
 </pre>
@@ Line 822: / Line 776: @@
 add one: 3.2360679774998
 half: 1.6180339887499
+</pre>
+=={{header|zkl}}==
+{{trans|EchoLisp}}
+<lang zkl>class Writer{
+   fcn init(x){ var X=x, logText=Data(Void,"  init \U2192; ",x.toString()) }
+   fcn unit(text)  { logText.append(text); self }
+   fcn lift(f,name){ unit("\n  %s \U2192; %s".fmt(name,X=f(X))) }
+   fcn bind(f,name){ lift.fp(f,name) }
+   fcn toString{ "Result = %s\n%s".fmt(X,logText.text) }
+   fcn root{ lift(fcn(x){ x.sqrt() },"root") }
+   fcn half{ lift('/(2),"half") }
+   fcn inc { lift('+(1),"inc") }
+}</lang>
+<lang zkl>Writer(5.0).root().inc().half().println();</lang>
+{{out}}
+<pre>
+Result = 1.61803
+  init → 5
+  root → 2.23607
+  inc → 3.23607
+  half → 1.61803
+</pre>
+<lang zkl>w:=Writer(5.0);
+Utils.Helpers.fcomp(w.half,w.inc,w.root)(w).println();  // half(inc(root(w)))</lang>
+{{out}}
+<pre>
+Result = 1.61803
+  init → 5
+  root → 2.23607
+  inc → 3.23607
+  half → 1.61803
+</pre>
+Use bind to add functions to an existing Writer:
+<lang zkl>w:=Writer(5.0);
+root,inc,half := w.bind(fcn(x){ x.sqrt() },"root"), w.bind('+(1),"+ 1"), w.bind('/(2),"/ 2");
+root(); inc(); half(); w.println();</lang>
+{{out}}
+<pre>
+Result = 1.61803
+  init → 5
+  root → 2.23607
+  + 1 → 3.23607
+  / 2 → 1.61803
 </pre>