From d22f2647e2f850879f0bdb9db196b5a4130bbf97 Mon Sep 17 00:00:00 2001
From: Rigidity <me@rigidnetwork.com>
Date: Mon, 24 Jun 2024 08:52:54 -0400
Subject: [PATCH 1/2] Functional programming utilities

---
 .../rue-compiler/src/database/type_system.rs  |  8 ++++---
 std/stdlib.rue                                | 24 +++++++++++++++++++
 tests/stdlib/fp_utils.rue                     |  4 ++++
 3 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 tests/stdlib/fp_utils.rue

diff --git a/crates/rue-compiler/src/database/type_system.rs b/crates/rue-compiler/src/database/type_system.rs
index ab36c6d..e59e918 100644
--- a/crates/rue-compiler/src/database/type_system.rs
+++ b/crates/rue-compiler/src/database/type_system.rs
@@ -220,7 +220,7 @@ impl Database {
             (Type::Alias(..), _) | (_, Type::Alias(..)) => unreachable!(),
 
             // We need to infer `Generic` types, and return `Unrelated` if incompatible.
-            (_, Type::Generic) if ctx.infer_generics => {
+            (_, Type::Generic) => {
                 let mut found = None;
 
                 for generics in ctx.generic_type_stack.iter().rev() {
@@ -231,9 +231,11 @@ impl Database {
 
                 if let Some(found) = found {
                     self.compare_type_visitor(lhs, found, ctx)
-                } else {
+                } else if ctx.infer_generics {
                     ctx.generic_type_stack.last_mut().unwrap().insert(rhs, lhs);
                     Comparison::Assignable
+                } else {
+                    Comparison::Unrelated
                 }
             }
 
@@ -264,7 +266,7 @@ impl Database {
 
             // `Generic` types are unrelated to everything else except their specific instance.
             // The only exception is the `Any` type above.
-            (Type::Generic, _) | (_, Type::Generic) => Comparison::Unrelated,
+            (Type::Generic, _) => Comparison::Unrelated,
 
             // You have to explicitly convert between other atom types.
             // This is because the compiled output can change depending on the type.
diff --git a/std/stdlib.rue b/std/stdlib.rue
index 0b0f01c..108ca2d 100644
--- a/std/stdlib.rue
+++ b/std/stdlib.rue
@@ -196,3 +196,27 @@ export fun calculate_coin_id(
     assert puzzle_hash is Bytes32;
     sha256(parent_coin_id + puzzle_hash + amount as Bytes)
 }
+
+export fun map<T, U>(list: T[], fn: fun(T) -> U) -> U[] {
+    if list is Nil {
+        return nil;
+    }
+    [fn(list.first), ...map(list.rest, fn)]
+}
+
+export fun filter<T>(list: T[], fn: fun(T) -> Bool) -> T[] {
+    if list is Nil {
+        return nil;
+    }
+    if fn(list.first) {
+        return [list.first, ...filter(list.rest, fn)];
+    }
+    filter(list.rest, fn)
+}
+
+export fun fold<T, U>(list: T[], initial: U, fn: fun(U, T) -> U) -> U {
+    if list is Nil {
+        return initial;
+    }
+    fold(list.rest, fn(initial, list.first), fn)
+}
diff --git a/tests/stdlib/fp_utils.rue b/tests/stdlib/fp_utils.rue
new file mode 100644
index 0000000..5fd07a6
--- /dev/null
+++ b/tests/stdlib/fp_utils.rue
@@ -0,0 +1,4 @@
+fun main() -> Nil {
+    assert tree_hash(map([1, 2, 3], fun(num: Int) => num * 2)) == tree_hash([2, 4, 6]);
+    nil
+}

From b8f5fed035e2cbfdb19b3b3f85ed0bfdf20e9492 Mon Sep 17 00:00:00 2001
From: Rigidity <me@rigidnetwork.com>
Date: Mon, 24 Jun 2024 08:56:30 -0400
Subject: [PATCH 2/2] Rest of test

---
 tests.toml                | 7 +++++++
 tests/stdlib/fp_utils.rue | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/tests.toml b/tests.toml
index c2bb852..0838dea 100644
--- a/tests.toml
+++ b/tests.toml
@@ -216,3 +216,10 @@ cost = 24974
 input = "(0xc00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 () (q . ((51 0x291e4594b43d58e833cab95e4b165c5fac6b4d8391c81ebfd20efdd8d58b92d8 1000))) 1)"
 output = "((g1_multiply 0xc00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 0x3d7e1145b5969c12f4889f4f1f66bde0e4d3ba54b91784cf604294d162b44b69) (g1_negate 0x291e4594b43d58e833cab95e4b165c5fac6b4d8391c81ebfd20efdd8d58b92d8 1000))"
 hash = "670f06e052dedc68788dd17acb7d100203a1533d11f9c679d0f23bd3d555f122"
+
+[fp_utils]
+bytes = 873
+cost = 92626
+input = "()"
+output = "()"
+hash = "5f8d285dbefef4c4c7ccfcc4f204710c21f46ea45bfe6d5b4e81562ef183adde"
diff --git a/tests/stdlib/fp_utils.rue b/tests/stdlib/fp_utils.rue
index 5fd07a6..0df9528 100644
--- a/tests/stdlib/fp_utils.rue
+++ b/tests/stdlib/fp_utils.rue
@@ -1,4 +1,6 @@
 fun main() -> Nil {
     assert tree_hash(map([1, 2, 3], fun(num: Int) => num * 2)) == tree_hash([2, 4, 6]);
+    assert tree_hash(filter([1, 2, 3, 4, 5], fun(num: Int) => num < 4)) == tree_hash([1, 2, 3]);
+    assert tree_hash(fold([1, 2, 3], 0, fun(acc: Int, num: Int) => acc + num)) == tree_hash(6);
     nil
 }