Data update

Task/Monads-Maybe-monad/ALGOL-68/monads-maybe-monad.alg

@@ -79,9 +79,9 @@ COMMENT
 
     # Using the bind function, we can nest applications of safe functions,                     #
     # without the compiler choking on unexpectedly wrapped values returned from                #
-    # other functions of the same kind.                                                        #
-    REAL root one over four = value OF ( MAYBE( TRUE, 4 ) BIND safe reciprocal BIND safe root );
-
+    # other functions of the same kind. E.g.:                                                  #
+#   REAL root one over four                                                                    #
+#      = value OF ( MAYBE( TRUE, 4 ) BIND safe reciprocal BIND safe root );                    #
 #   print( ( root one over four, newline ) ); #
     # -> 0.5 #
 

Task/Monads-Maybe-monad/J/monads-maybe-monad-1.j

@@ -0,0 +1,3 @@
+'J N'=. s:'Just';'Nothing'
+unit =. J,&<]
+bind =. {{u@(1{::])^:(N-.@-:])}}

Task/Monads-Maybe-monad/J/monads-maybe-monad-2.j

@@ -0,0 +1,3 @@
+fail =. {{unit@:u`(N"_)@.v}}              NB. if v —> return Nothing, else apply u
+show =. [: ": (,' '&,)&":&>/
+comp =. [: > {{<x`:6 bind>y}}/@(,<@unit)  NB. multi-compose

Task/Monads-Maybe-monad/J/monads-maybe-monad-3.j

@@ -0,0 +1,14 @@
+   ^.%:_2                                 NB. ln ∘ sqrt; gives complex numbers for inputs < 0
+0.346574j1.5708
+   sqrt=. %: fail ([: +./ <&0)            NB. return Nothing where result would've been complex
+   ln  =. ^. fail ([: +./ <:&0)           NB. same
+   show ln bind sqrt bind unit 2 3 4
+`Just 0.346574 0.549306 0.693147
+   show ln bind sqrt bind unit 2 _3 4     NB. short-circuits on input < 0
+`Nothing
+   show@(ln bind)@(sqrt bind)@unit&> 2 _3 4
+`Just 0.346574
+`Nothing
+`Just 0.693147
+   show unit@:*:`ln`sqrt comp 2 3 4
+`Just 0.120113 0.301737 0.480453

Task/Monads-Maybe-monad/J/monads-maybe-monad.j

@@ -1,27 +0,0 @@
-NB. monad implementation:
-unit=: <
-bind=: (@>)( :: ])
-
-NB. monad utility
-safeVersion=: (<@) ( ::((<_.)"_))
-safeCompose=:dyad define
-  dyad def 'x`:6 bind y'/x,unit y
-)
-
-NB. unsafe functions (fail with infinite arguments)
-subtractFromSelf=: -~
-divideBySelf=: %~
-
-NB. wrapped functions:
-safeSubtractFromSelf=: subtractFromSelf safeVersion
-safeDivideBySelf=: divideBySelf safeVersion
-
-NB. task example:
-     safeSubtractFromSelf bind safeDivideBySelf 1
-┌─┐
-│0│
-└─┘
-     safeSubtractFromSelf bind safeDivideBySelf _
-┌──┐
-│_.│
-└──┘

Task/Monads-Maybe-monad/K/monads-maybe-monad.k

@@ -0,0 +1,3 @@
+unit:(::)
+bind:{[k;a]:[a~`N;a;k a]}
+kcomp:{[f;g](bind[g;]@f@)} / (>=>) i.e. kleisli composition

Task/Monads-Maybe-monad/V-(Vlang)/monads-maybe-monad.v

@@ -0,0 +1,17 @@
+type Maybe = f64 | string
+
+fn (m Maybe) div(x f64, y f64) Maybe {
+	mut result := m{}
+	result = x / y
+	if result.str().contains_any_substr(["inf","nan"]) {result = "none"}
+	return result
+}
+
+fn main() {
+	mb := Maybe{}
+	for a in [15, 0, 5] {
+		for b in [5, 0, 0] {
+			println(mb.div(a, b))
+		}
+	}
+}