Data update

Task/Monads-Maybe-monad/FreeBASIC/monads-maybe-monad.basic

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+Type mmaybe
+    As Integer value
+End Type
+
+Function Bindf(m As mmaybe, f As Function(As mmaybe) As mmaybe) As mmaybe
+    Return f(m)
+End Function
+
+Function Unit(i As Integer) As mmaybe
+    Dim As mmaybe m
+    m.value = i
+    Return m
+End Function
+
+Function Decrement(mm As mmaybe) As mmaybe
+    Dim As mmaybe result
+    result.value = Iif(mm.value = 0, 0, mm.value - 1)
+    Return Unit(result.value)
+End Function
+
+Function Triple(mm As mmaybe) As mmaybe
+    Dim As mmaybe result
+    result.value = Iif(mm.value = 0, 0, 3 * mm.value)
+    Return Unit(result.value)
+End Function
+
+Dim As Integer values(3) = {3, 4, 0, 5}
+Dim As Function(As mmaybe) As mmaybe Ptr decrementPtr = @Decrement
+Dim As Function(As mmaybe) As mmaybe Ptr triplePtr = @Triple
+
+For i As Integer = Lbound(values) To Ubound(values)
+    Dim As mmaybe m1 = Unit(values(i))
+    Dim As mmaybe m2 = Bindf(Bindf(m1, decrementPtr), triplePtr)
+    Dim As String s1 = Iif(m1.value = 0, "none", Str(m1.value))
+    Dim As String s2 = Iif(m2.value = 0, "none", Str(m2.value))
+    Print Using "\  \ -> \  \"; s1; s2
+Next i
+
+Sleep