From ac50bb70e668c55392bc2e9210e44e12a9ae0021 Mon Sep 17 00:00:00 2001
From: ivanjermakov <ivanjermakov1@gmail.com>
Date: Fri, 19 Apr 2024 13:27:42 +0200
Subject: [PATCH] Std: `Future::map`, `Future::flatMap`

---
 src/semantic/index.ts |  2 ++
 src/std/future.no     | 24 +++++++++++++++++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/semantic/index.ts b/src/semantic/index.ts
index da4746fe..3d969caa 100644
--- a/src/semantic/index.ts
+++ b/src/semantic/index.ts
@@ -335,6 +335,8 @@ const checkFnDef = (fnDef: FnDef, ctx: Context): void => {
     }
     enterScope(module, fnScope, ctx)
 
+    // TODO: find await-ops and decide whether fn is awaiting
+
     const paramTypes = fnDef.params.map((p, i) => {
         checkParam(p, i, ctx)
         return p.type!
diff --git a/src/std/future.no b/src/std/future.no
index 84df01d5..9f0a01bd 100644
--- a/src/std/future.no
+++ b/src/std/future.no
@@ -21,16 +21,32 @@ impl <T> Future<T> {
         Future(f, [], Created())
     }
 
-    pub fn onResolve(self, f: |T|: Unit): Self {
+    pub fn onResolve(self, f: |T|: Unit): Unit {
         match self.state {
             Resolved(value) {
                 f(value)
-                return self
+                return unit
+            }
+            Created() {
+                self.spawn(runtime)
             }
             _ {}
         }
         self.subscribers.add(f)
-        self
+    }
+
+    // TODO: belongs to std::control::Functor
+    pub fn map<U>(self, f: |T|: U): Future<U> {
+        // TODO: use .await
+        Future::new(|resolve| self.onResolve(|res| resolve(f(res))))
+    }
+
+    // TODO: belongs to std::control::Monad
+    pub fn flatMap<U>(self, f: |T|: Future<U>): Future<U> {
+        // TODO: use .await
+        Future::new(|resolve| {
+            self.onResolve(|res| f(res).onResolve(|inner| resolve(inner)))
+        })
     }
 
     pub fn spawn(self, runtime: Runtime): Self {
@@ -45,6 +61,8 @@ pub type Runtime(
     pending: List<Future<_>>,
 )
 
+pub let runtime: Runtime = Runtime::new()
+
 impl Runtime {
     pub fn new(): Runtime {
         Runtime::withPollingRate(10)