Data update

Task/Church-numerals/Go/church-numerals-2.go

@@ -0,0 +1,88 @@
+package main
+
+import "fmt"
+
+type Church func(Church) Church
+
+func id[X any](x X) X {
+  return x
+}
+
+func compose[X any, Y any, Z any](f func(Y) Z, g func(X) Y) func(X) Z {
+  return func(x X) Z {
+    return f(g(x))
+  }
+}
+
+func zero() Church {
+  return func(f Church) Church {
+    return id[Church]
+  }
+}
+
+func one() Church {
+  return id[Church]
+}
+
+func succ(n Church) Church {
+  return func(f Church) Church {
+    return compose(f, n(f))
+  }
+}
+
+func plus(m, n Church) Church {
+  return func(f Church) Church {
+    return compose(m(f), n(f))
+  }
+}
+
+func mult(m, n Church) Church {
+  return compose(m, n)
+}
+
+func exp(m, n Church) Church {
+  return n(m)
+}
+
+func toInt(x Church) int {
+  counter := 0
+  fCounter := func(f Church) Church {
+    counter++
+    return f
+  }
+
+  x(fCounter)(id[Church])
+  return counter
+}
+
+func toStr(x Church) string {
+  counter := ""
+  fCounter := func(f Church) Church {
+    counter += "|"
+    return f
+  }
+
+  x(fCounter)(id[Church])
+  return counter
+}
+
+func main() {
+  fmt.Println("zero =", toInt(zero()))
+
+  one := one()
+  fmt.Println("one =", toInt(one))
+
+  two := succ(succ(zero()))
+  fmt.Println("two =", toInt(two))
+
+  three := plus(one, two)
+  fmt.Println("three =", toInt(three))
+
+  four := mult(two, two)
+  fmt.Println("four =", toInt(four))
+
+  eight := exp(two, three)
+  fmt.Println("eight =", toInt(eight))
+
+  fmt.Println("toStr(four) =", toStr(four))
+}