From efe0ab336144d2d965bf355db02762f5cf539c7f Mon Sep 17 00:00:00 2001
From: Akshay Nair <phenax5@gmail.com>
Date: Sat, 14 Jan 2023 10:37:51 +0530
Subject: feat: adds func to try/catch

---
 examples/file.ts         | 13 +++++++------
 src/eval-env/builtins.ts | 18 +++++++++---------
 stdlib/effect.ts         |  2 +-
 stdlib/exception.ts      |  4 ++--
 stdlib/util.ts           |  9 +++++++--
 5 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/examples/file.ts b/examples/file.ts
index 2cc2b7a..5af04da 100644
--- a/examples/file.ts
+++ b/examples/file.ts
@@ -7,11 +7,12 @@ interface PrintK extends Kind1<string> {
   return: PutStringLn<this['input']>
 }
 
-interface ConstK<Val> extends Kind1<unknown, Val> {
-  return: Val
-}
-
 export type main = [
-  Bind<ReadFile<'./default.nix'>, PrintK>,
-  Bind<Try<ReadFile<'./unicorn'>, ConstK<'hello world'>>, PrintK>
+  Bind<ReadFile<'./default.nix'>, <contents extends string>() =>
+    PutStringLn<contents>>,
+
+  Try<
+    Bind<ReadFile<'./unicorn'>, PrintK>,
+    <M extends string>() => PutStringLn<`ERROR: ${M}`>
+  >
 ]
diff --git a/src/eval-env/builtins.ts b/src/eval-env/builtins.ts
index f67fcc6..ed94943 100644
--- a/src/eval-env/builtins.ts
+++ b/src/eval-env/builtins.ts
@@ -31,7 +31,12 @@ const applyFunc = (ctx: Ctx, fn: Type | undefined, val: string): Type => {
         const typeParameters = functionNode.getTypeParameters() ?? []
 
         if (typeParameters.length > 0) {
-          typeParameters[0]?.getConstraint()?.replaceWithText(val)
+          const constraint = typeParameters[0]?.getConstraint()
+          if (constraint) {
+            constraint?.replaceWithText(val)
+          } else {
+            typeParameters[0]?.setConstraint(val)
+          }
         }
 
         return resValueNode?.getType()
@@ -126,9 +131,7 @@ export default (ctx: Ctx, args: Type[]) => ({
 
     const resultType =
       applyFunc(ctx, chainToKind, `(${ctx.getResultExpr(resultKey)})['output']`)
-    const res = await ctx.evaluateType(ctx, resultType)
-
-    return res
+    return ctx.evaluateType(ctx, resultType)
   },
 
   Try: async () => {
@@ -139,11 +142,8 @@ export default (ctx: Ctx, args: Type[]) => ({
       return await ctx.evaluateType(ctx, effTyp)
     } catch (e) {
       const error = JSON.stringify((e as any)?.message ?? e)
-      const catchResExpr = `(${ctx.typeToString(
-        catchK
-      )} & { input: ${error} })['return']`
-      const [resultKey, _] = ctx.createResult(catchResExpr)
-      return [resultKey]
+      const resultType = applyFunc(ctx, catchK, error)
+      return ctx.evaluateType(ctx, resultType)
     }
   },
 
diff --git a/stdlib/effect.ts b/stdlib/effect.ts
index 0662d00..341a620 100644
--- a/stdlib/effect.ts
+++ b/stdlib/effect.ts
@@ -7,7 +7,7 @@ export interface Kind1<Inp = unknown, Out = unknown> {
   return: Out
 }
 
-type Func<Inp = unknown, Out = unknown>
+export type Func<Inp = unknown, Out = unknown>
   = Kind1<Inp, Out>
   | (<_T extends Inp>() => Out)
 
diff --git a/stdlib/exception.ts b/stdlib/exception.ts
index ddb980c..d137a87 100644
--- a/stdlib/exception.ts
+++ b/stdlib/exception.ts
@@ -1,5 +1,5 @@
-import { Effect, Kind1 } from './effect'
+import { Effect, Func } from './effect'
 
-export interface Try<_E extends Effect, _Catch extends Kind1> extends Effect {}
+export interface Try<_E extends Effect, _Catch extends Func> extends Effect {}
 
 export interface Throw<_E> extends Effect {}
diff --git a/stdlib/util.ts b/stdlib/util.ts
index 20a41fb..cd25d7b 100644
--- a/stdlib/util.ts
+++ b/stdlib/util.ts
@@ -2,12 +2,17 @@ import { Kind1 } from './effect'
 
 export type Let<f extends (...args: any) => any> = ReturnType<f>
 
-export type Apply<K extends Kind1, Val> = (K & { input: Val })['return']
+export type ApplyK<K extends Kind1, Val> = (K & { input: Val })['return']
 
-export interface Id extends Kind1 {
+export type Id = <T>() => T
+export interface IdK extends Kind1 {
   return: this['input']
 }
 
+export interface ConstK<Val> extends Kind1<unknown, Val> {
+  return: Val
+}
+
 type ADTDescr = { _type: string; value: any }
 
 interface ADTConstructor<A extends ADTDescr> extends Kind1<A['value']> {
-- 
cgit v1.3.1