Working example

src/external/str/concatenate.rs

@@ -0,0 +1,41 @@
+use super::cls2str;
+
+use std::fmt::Debug;
+use std::hash::Hash;
+
+use crate::{atomic_impl, atomic_redirect, externfn_impl};
+use crate::representations::{Primitive, Literal};
+use crate::representations::interpreted::Clause;
+
+/// Concatenate function
+/// 
+/// Next state: [Concatenate1]
+
+#[derive(Clone)]
+pub struct Concatenate2;
+externfn_impl!(Concatenate2, |_: &Self, c: Clause| {Ok(Concatenate1{c})});
+
+/// Partially applied Concatenate function
+/// 
+/// Prev state: [Concatenate2]; Next state: [Concatenate0]
+
+#[derive(Debug, Clone, PartialEq, Hash)]
+pub struct Concatenate1{ c: Clause }
+atomic_redirect!(Concatenate1, c);
+atomic_impl!(Concatenate1);
+externfn_impl!(Concatenate1, |this: &Self, c: Clause| {
+  let a: String = cls2str(&this.c)?.clone();
+  Ok(Concatenate0{ a, c })
+});
+
+/// Fully applied Concatenate function.
+/// 
+/// Prev state: [Concatenate1]
+
+#[derive(Debug, Clone, PartialEq, Hash)]
+pub struct Concatenate0 { a: String, c: Clause }
+atomic_redirect!(Concatenate0, c);
+atomic_impl!(Concatenate0, |Self{ a, c }: &Self| {
+  let b: &String = cls2str(c)?;
+  Ok(Clause::P(Primitive::Literal(Literal::Str(a.to_owned() + b))))
+});