Syntax: single statement closure

README.md

@@ -39,7 +39,7 @@ pub fn main() {
     println(
         shapes
             .iter()
-            .map(|s| { s.area() })
+            .map(|s| s.area())
             .collect<List<_>>()
             .show()
     )

data/features.no

@@ -122,8 +122,8 @@ fn main() {
     }
 
     // closure
-    let square: |Num|: Num = |a| { a^2 }
-    let here = || { println("here") }
+    let square: |Num|: Num = |a| a^2
+    let here = || println("here")
 
     // fn reference
     let p = println

example/example.no

@@ -26,7 +26,7 @@ pub fn main() {
     println(
         shapes
             .iter()
-            .map(|s| { s.area() })
+            .map(|s| s.area())
             .collect<List<_>>()
             .show()
     )

example/rule110.no

@@ -33,7 +33,7 @@ fn fmtGen(gen: List<Bool>, total: Int): String {
     let pad = repeat(" ", total - gen.iter().count()).collect<String>()
     let g = gen
         .iter()
-        .map(|b| { if b { "x" } else { " " } })
+        .map(|b| if b { "x" } else { " " })
         .collect<String>()
     pad.concat(g)
 }

nois.bnf

@@ -101,7 +101,7 @@ type                  ::= type-bounds | fn-type | hole
                       ;
 block                 ::= O-BRACE statement* C-BRACE
                       ;
-closure-expr          ::= closure-params type-annot? block
+closure-expr          ::= closure-params type-annot? (block | statement)
                       ;
   closure-params      ::= PIPE (param (COMMA param)*)? COMMA? PIPE
                       ;

src/ast/operand.ts

@@ -7,7 +7,7 @@ import { assert } from '../util/todo'
 import { Expr, buildExpr } from './expr'
 import { AstNode, Param, buildParam } from './index'
 import { MatchExpr, Pattern, buildMatchExpr, buildNumber, buildPattern } from './match'
-import { Block, buildBlock } from './statement'
+import { Block, buildBlock, buildStatement } from './statement'
 import { Type, buildType } from './type'
 
 export type Operand = (
@@ -158,7 +158,10 @@ export const buildClosureExpr = (node: ParseNode): ClosureExpr => {
         .filter(n => n.kind === 'param')
         .map(n => buildParam(n))
     const returnType = nodes.at(idx)?.kind === 'type-annot' ? buildType(nodes[idx++]) : undefined
-    const block = buildBlock(nodes[idx++])
+    const block: Block =
+        nodes[idx].kind === 'block'
+            ? buildBlock(nodes[idx++])
+            : { kind: 'block', parseNode: nodes[idx], statements: [buildStatement(nodes[idx++])] }
     return { kind: 'closure-expr', parseNode: node, params, block, returnType }
 }
 

src/e2e.spec.ts

@@ -169,7 +169,7 @@ pub fn main() {
     println(
         shapes
             .iter()
-            .map(|s| { s.area() })
+            .map(|s| s.area())
             .collect<List<_>>()
             .show()
     )
@@ -220,7 +220,7 @@ fn fmtGen(gen: List<Bool>, total: Int): String {
     let pad = repeat(" ", total - gen.iter().count()).collect<String>()
     let g = gen
         .iter()
-        .map(|b| { if b { "x" } else { " " } })
+        .map(|b| if b { "x" } else { " " })
         .collect<String>()
     pad.concat(g)
 }`

src/parser/fns/index.ts

@@ -1,5 +1,4 @@
 import { Parser } from '..'
-import { syntaxError } from '../../error'
 import { TokenKind, lexerKeywordKinds } from '../../lexer/lexer'
 import { parseBlock, parseParam, parseStatement, parseUseStmt } from './statement'
 import { parseTypeAnnot } from './type'
@@ -60,7 +59,7 @@ export const parseModule = (parser: Parser): void => {
 
 /**
  * TODO: closure generics
- * closure-expr ::= closure-params type-annot? block
+ * closure-expr ::= closure-params type-annot? (block | statement)
  */
 export const parseClosureExpr = (parser: Parser): void => {
     const mark = parser.open()
@@ -71,7 +70,7 @@ export const parseClosureExpr = (parser: Parser): void => {
     if (parser.at('o-brace')) {
         parseBlock(parser)
     } else {
-        parser.advanceWithError(syntaxError(parser, 'expected block'))
+        parseStatement(parser)
     }
     parser.close(mark, 'closure-expr')
 }

src/semantic/semantic.spec.ts

@@ -562,7 +562,7 @@ fn main() {
             const code = `\
 fn main() {
     while true {
-        (|| { break })()
+        (|| break)()
     }
 }`
             const ctx = check(code)
@@ -611,7 +611,7 @@ type Foo(x: ||: Int)
 
 impl Foo {
     fn main() {
-        let foo = Foo::Foo(|| { 5 })
+        let foo = Foo::Foo(|| 5)
         let a = (foo.x)()
         a()
         return unit

src/std/future.no

@@ -65,12 +65,12 @@ impl Runtime {
                     s(res)
                 }
                 next.subscribers.clear()
-                self.pending.popAt(self.pending.iter().position(|e| { eqRef(next, e) })!)
+                self.pending.popAt(self.pending.iter().position(|e| eqRef(next, e))!)
                 unit
             })
         }
         if self.queue.count() > 0 || self.pending.count() > 0 {
-            deferFor(|| { self.loop() }, self.pollingRate)
+            deferFor(|| self.loop(), self.pollingRate)
         }
     }
 

src/std/iter/mod.no

@@ -13,7 +13,7 @@ pub trait Iter<T> {
     fn next(self): Option<T>
 
     fn count(self): Int {
-        self.fold(|acc, _| { acc + 1 }, 0)
+        self.fold(|acc, _| acc + 1, 0)
     }
 
     fn last(self): Option<T> {

src/std/string.no

@@ -40,7 +40,7 @@ impl Collector<String> for String {
 impl Collector<Char> for String {
     fn fromIter(iter: Iter<Char>): Self {
         // TODO: method ref
-        iter.map(|c| { c.show() }).collect<String>()
+        iter.map(|c| c.show()).collect<String>()
     }
 }