Monads/Writer monad: Difference between revisions
Added Go
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Line 197:
half → 1
</lang>
=={{header|Go}}==
{{trans|Kotlin}}
<lang go>package main
import (
"fmt"
"math"
)
type mwriter struct {
value float64
log string
}
func (m mwriter) bind(f func(v float64) mwriter) mwriter {
n := f(m.value)
n.log = m.log + n.log
return n
}
func unit(v float64, s string) mwriter {
return mwriter{v, fmt.Sprintf(" %-17s: %g\n", s, v)}
}
func root(v float64) mwriter {
return unit(math.Sqrt(v), "Took square root")
}
func addOne(v float64) mwriter {
return unit(v+1, "Added one")
}
func half(v float64) mwriter {
return unit(v/2, "Divided by two")
}
func main() {
mw1 := unit(5, "Initial value")
mw2 := mw1.bind(root).bind(addOne).bind(half)
fmt.Println("The Golden Ratio is", mw2.value)
fmt.Println("\nThis was derived as follows:-")
fmt.Println(mw2.log)
}</lang>
{{out}}
<pre>
The Golden Ratio is 1.618033988749895
This was derived as follows:-
Initial value : 5
Took square root : 2.23606797749979
Added one : 3.23606797749979
Divided by two : 1.618033988749895
</pre>
=={{header|Haskell}}==
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