15 files changed, 114 insertions, 56 deletions

diff --git a/ast/src/main/java/lv/enes/orang/ast/ArgSpec.java b/ast/src/main/java/lv/enes/orang/ast/ArgSpec.java
new file mode 100644
index 0000000..e167e8f
--- /dev/null
+++ b/ast/src/main/java/lv/enes/orang/ast/ArgSpec.java
@@ -0,0 +1,26 @@
+package lv.enes.orang.ast;
+
+public class ArgSpec {
+        public final Type type;
+        public final String name;
+
+        private static final ArgSpec NOTHING = new ArgSpec(Type.NOTHING, null);
+
+        public static ArgSpec nothing() {
+                return NOTHING;
+        }
+
+        public static ArgSpec named(String name) {
+                return new ArgSpec(Type.NAMED, name);
+        }
+
+        private ArgSpec(Type type, String name) {
+                this.type = type;
+                this.name = name;
+        }
+
+        public enum Type {
+                NOTHING,
+                NAMED,
+        }
+}
diff --git a/ast/src/main/java/lv/enes/orang/ast/DefSpec.java b/ast/src/main/java/lv/enes/orang/ast/DefSpec.java
index 2233d3f..5e6cc68 100644
--- a/ast/src/main/java/lv/enes/orang/ast/DefSpec.java
+++ b/ast/src/main/java/lv/enes/orang/ast/DefSpec.java
@@ -2,5 +2,5 @@ package lv.enes.orang.ast;
 
 import java.util.List;
 
-public record DefSpec(String name, List<String> args) {
+public record DefSpec(String name, List<ArgSpec> args) {
 }
diff --git a/ast/src/main/java/lv/enes/orang/ast/ExpressionVisitor.java b/ast/src/main/java/lv/enes/orang/ast/ExpressionVisitor.java
index ddb1157..70f8a5e 100644
--- a/ast/src/main/java/lv/enes/orang/ast/ExpressionVisitor.java
+++ b/ast/src/main/java/lv/enes/orang/ast/ExpressionVisitor.java
@@ -19,4 +19,5 @@ public interface ExpressionVisitor<R, E extends OrangException> {
         R visitStringLiteral(StringLiteral expr) throws E;
         R visitUnaryExpression(UnaryExpression expr) throws E;
         R visitVariable(VariableExpression expr) throws E;
+        R visitVoidExpression() throws E;
 }
diff --git a/ast/src/main/java/lv/enes/orang/ast/FnExpression.java b/ast/src/main/java/lv/enes/orang/ast/FnExpression.java
index 68f43af..0bf322c 100644
--- a/ast/src/main/java/lv/enes/orang/ast/FnExpression.java
+++ b/ast/src/main/java/lv/enes/orang/ast/FnExpression.java
@@ -3,7 +3,7 @@ package lv.enes.orang.ast;
 import lv.enes.orang.utils.NonEmptyList;
 import lv.enes.orang.core.OrangException;
 
-public record FnExpression(NonEmptyList<String> args, Expression body) implements Expression {
+public record FnExpression(NonEmptyList<ArgSpec> args, Expression body) implements Expression {
         @Override
         public <R, E extends OrangException> R accept(ExpressionVisitor<R, E> visitor) throws E {
                 return visitor.visitFnExpression(this);
diff --git a/ast/src/main/java/lv/enes/orang/ast/VoidExpression.java b/ast/src/main/java/lv/enes/orang/ast/VoidExpression.java
new file mode 100644
index 0000000..39d164d
--- /dev/null
+++ b/ast/src/main/java/lv/enes/orang/ast/VoidExpression.java
@@ -0,0 +1,14 @@
+package lv.enes.orang.ast;
+
+import lv.enes.orang.core.OrangException;
+
+public final class VoidExpression implements Expression {
+        public static final VoidExpression INSTANCE = new VoidExpression();
+
+        private VoidExpression() {}
+
+        @Override
+        public <R, E extends OrangException> R accept(ExpressionVisitor<R, E> visitor) throws E {
+                return visitor.visitVoidExpression();
+        }
+}
diff --git a/dice.orang b/dice.orang
index 0fae27b..d8e52de 100644
--- a/dice.orang
+++ b/dice.orang
@@ -1,14 +1,14 @@
 def dice sides times =
-  let once _ = randInt 1 (sides + 1) in
+  let once () = randInt 1 (sides + 1) in
   let aux acc times =
     if times ?= 0 then acc
     else aux (acc + once ()) (times - 1)
   in
   aux 0 times
 
-def guessing_game _ =
+def guessing_game () =
   let secret = randInt 1 101
-  and guessOnce _ = do
+  and guessOnce () = do
     print "Make your guess: ";
     let guess = readInt () in
     if secret > guess then do
diff --git a/grammar.bnf b/grammar.bnf
index 7c18f8f..9ddaffc 100644
--- a/grammar.bnf
+++ b/grammar.bnf
@@ -4,7 +4,7 @@ program ::= (statement ';'?)*;
 statement ::= definition | expression;
 definition ::= 'def' def-spec '=' expression;
 def-spec ::= IDENTIFIER arg-spec*;
-arg-spec ::= IDENTIFIER;
+arg-spec ::= IDENTIFIER | '(' ')';
 expression ::= binary-expression | unary-expression;
 unary-expression ::= unop+ simple-expression;
 binary-expression ::= call-expression (binop call-expression)*;
@@ -13,6 +13,7 @@ binop ::= '*' | '/' | '+' | '-' | '?=' | '/=' | '>' | '>=' | '<' | '<=';
 unop ::= '+' | '-' | '!';
 simple-expression ::= '(' expression ')'
                     | 'true' | 'false'
+                    | '(' ')'
                     | INTEGER
                     | IDENTIFIER
                     | STRING
@@ -22,7 +23,7 @@ simple-expression ::= '(' expression ')'
                     | fn-expression
                     | do-expression;
 
-array ::= '(' ')' | '[' ']' | '[' expression (',' expression)* ','? ']';
+array ::= '[' ']' | '[' expression (',' expression)* ','? ']';
 
 if-else-expression ::= 'if' expression 'then' expression 'else' expression;
 let-in-expression ::= 'let' def-spec '=' expression ('and' def-spec '=' expression)* 'in' expression;
diff --git a/orang/src/main/java/lv/enes/orang/Builtins.java b/orang/src/main/java/lv/enes/orang/Builtins.java
index 0a76387..de296ac 100644
--- a/orang/src/main/java/lv/enes/orang/Builtins.java
+++ b/orang/src/main/java/lv/enes/orang/Builtins.java
@@ -79,13 +79,6 @@ public final class Builtins {
         }
 
         private static Value readLn(List<Value> args) throws OrangRuntimeException {
-                assert args.size() == 1;
-
-                var arg = args.getFirst();
-                if (!(arg instanceof Array) || !((Array) arg).items().isEmpty()) {
-                        log.warn("You should call readLn with an empty tuple like `readLn ()`");
-                }
-
                 try {
                         return new OrangString(STDIN.readLine());
                 } catch (IOException e) {
diff --git a/orang/src/main/java/lv/enes/orang/Evaluator.java b/orang/src/main/java/lv/enes/orang/Evaluator.java
index e2e96ff..5d09508 100644
--- a/orang/src/main/java/lv/enes/orang/Evaluator.java
+++ b/orang/src/main/java/lv/enes/orang/Evaluator.java
@@ -141,4 +141,9 @@ public record Evaluator(Scope scope, Value lastResult) implements ExpressionVisi
         public Value visitVariable(VariableExpression expr) throws OrangRuntimeException {
                 return scope.getDefinition(expr.name());
         }
+
+        @Override
+        public Value visitVoidExpression() {
+                return Nothing.INSTANCE;
+        }
 }
diff --git a/orang/src/main/java/lv/enes/orang/Parser.java b/orang/src/main/java/lv/enes/orang/Parser.java
index 4011bd7..77abe24 100644
--- a/orang/src/main/java/lv/enes/orang/Parser.java
+++ b/orang/src/main/java/lv/enes/orang/Parser.java
@@ -91,11 +91,15 @@ public class Parser {
                 return new ArrayExpression(Collections.unmodifiableList(items));
         }
 
-        private List<String> parseArgSpecs() {
-                var argSpecs = new ArrayList<String>();
+        private List<ArgSpec> parseArgSpecs() throws ParserException {
+                var argSpecs = new ArrayList<ArgSpec>();
                 while (true) {
                         if (input.peek().type() == TokenType.IDENTIFIER) {
-                                argSpecs.add(input.next().literal());
+                                argSpecs.add(ArgSpec.named(input.next().literal()));
+                        } else if (input.peek().type() == TokenType.PAREN_LEFT) {
+                                consumeToken(TokenType.PAREN_LEFT);
+                                consumeToken(TokenType.PAREN_RIGHT);
+                                argSpecs.add(ArgSpec.nothing());
                         } else {
                                 break;
                         }
@@ -224,7 +228,7 @@ public class Parser {
                         case PAREN_LEFT -> {
                                 consumeToken(TokenType.PAREN_LEFT);
                                 if (maybeConsumeToken(TokenType.PAREN_RIGHT)) {
-                                        yield new ArrayExpression(List.of());
+                                        yield VoidExpression.INSTANCE;
                                 }
                                 var expr = parseExpression();
                                 consumeToken(TokenType.PAREN_RIGHT);
diff --git a/orang/src/main/java/lv/enes/orang/value/Function.java b/orang/src/main/java/lv/enes/orang/value/Function.java
index 901776e..6e3c83a 100644
--- a/orang/src/main/java/lv/enes/orang/value/Function.java
+++ b/orang/src/main/java/lv/enes/orang/value/Function.java
@@ -1,14 +1,11 @@
 package lv.enes.orang.value;
 
-import lv.enes.orang.Evaluator;
-import lv.enes.orang.ImmutableScope;
-import lv.enes.orang.OrangRuntimeException;
-import lv.enes.orang.Scope;
+import lv.enes.orang.*;
+import lv.enes.orang.ast.ArgSpec;
 import lv.enes.orang.ast.Expression;
+import lv.enes.orang.utils.NonEmptyList;
 
-import java.util.List;
-
-public record Function(Scope scope, List<String> args, Expression body) implements Value {
+public record Function(Scope scope, NonEmptyList<ArgSpec> args, Expression body) implements Value {
         @Override
         public String typeName() {
                 return "Function";
@@ -21,11 +18,6 @@ public record Function(Scope scope, List<String> args, Expression body) implemen
 
         @Override
         public Value call(Value param) throws OrangRuntimeException {
-                if (args.size() == 1) {
-                        var eval = new Evaluator(ImmutableScope.of(scope, args.getFirst(), param));
-                        return eval.visit(body);
-                } else {
-                        return new PartialFunction(scope, args, List.of(param), body);
-                }
+                return PartialFunction.of(scope, args, body, param);
         }
 }
diff --git a/orang/src/main/java/lv/enes/orang/value/Nothing.java b/orang/src/main/java/lv/enes/orang/value/Nothing.java
new file mode 100644
index 0000000..4a90010
--- /dev/null
+++ b/orang/src/main/java/lv/enes/orang/value/Nothing.java
@@ -0,0 +1,21 @@
+package lv.enes.orang.value;
+
+import lombok.EqualsAndHashCode;
+
+@EqualsAndHashCode
+public final class Nothing implements Value {
+        public static final Nothing INSTANCE = new Nothing();
+
+        private Nothing() {
+        }
+
+        @Override
+        public String typeName() {
+                return "Nothing";
+        }
+
+        @Override
+        public String stringify() {
+                return "()";
+        }
+}
diff --git a/orang/src/main/java/lv/enes/orang/value/PartialFunction.java b/orang/src/main/java/lv/enes/orang/value/PartialFunction.java
index 0dbf530..cee0cd4 100644
--- a/orang/src/main/java/lv/enes/orang/value/PartialFunction.java
+++ b/orang/src/main/java/lv/enes/orang/value/PartialFunction.java
@@ -1,17 +1,30 @@
 package lv.enes.orang.value;
 
-import lv.enes.orang.Evaluator;
-import lv.enes.orang.ImmutableScope;
-import lv.enes.orang.OrangRuntimeException;
-import lv.enes.orang.Scope;
+import lv.enes.orang.*;
+import lv.enes.orang.ast.ArgSpec;
 import lv.enes.orang.ast.Expression;
+import lv.enes.orang.utils.NonEmptyList;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
+public record PartialFunction(Scope scope, NonEmptyList<ArgSpec> remainingArgs, Expression body) implements Value {
+        public static Value of(Scope scope, NonEmptyList<ArgSpec> remainingArgs, Expression body, Value param) throws OrangRuntimeException {
+                var spec = remainingArgs.getFirst();
+                var newScope = MutableScope.of(scope);
+                switch (spec.type) {
+                        case NAMED -> newScope.setDefinition(spec.name, param);
+                        case NOTHING -> {
+                                if (!(param instanceof Nothing)) {
+                                        throw new OrangRuntimeException(STR."Expected () as a parameter but got \{param.typeName()}");
+                                }
+                        }
+                }
+
+                if (remainingArgs.size() == 1) {
+                        return new Evaluator(newScope).visit(body);
+                } else {
+                        return new PartialFunction(newScope, new NonEmptyList<>(remainingArgs.subList(1, remainingArgs.size())), body);
+                }
+        }
 
-public record PartialFunction(Scope scope, List<String> args, List<Value> params, Expression body) implements Value {
         @Override
         public String typeName() {
                 return "Function";
@@ -24,17 +37,6 @@ public record PartialFunction(Scope scope, List<String> args, List<Value> params
 
         @Override
         public Value call(Value param) throws OrangRuntimeException {
-                var newParams = new ArrayList<>(params);
-                newParams.add(param);
-                if (newParams.size() == args.size()) {
-                        var newDefs = new HashMap<String, Value>();
-                        for (var i = 0; i < args.size(); i++) {
-                                newDefs.put(args.get(i), newParams.get(i));
-                        }
-                        var eval = new Evaluator(ImmutableScope.of(scope, newDefs));
-                        return eval.visit(body);
-                }
-
-                return new PartialFunction(scope, args, Collections.unmodifiableList(newParams), body);
+                return PartialFunction.of(scope, remainingArgs, body, param);
         }
 }
diff --git a/orang/src/main/java/lv/enes/orang/value/Value.java b/orang/src/main/java/lv/enes/orang/value/Value.java
index fa8275c..0816dc2 100644
--- a/orang/src/main/java/lv/enes/orang/value/Value.java
+++ b/orang/src/main/java/lv/enes/orang/value/Value.java
@@ -3,8 +3,7 @@ package lv.enes.orang.value;
 import lv.enes.orang.OrangRuntimeException;
 
 public sealed interface Value
-                permits Array, BuiltinFunction, Function, OrangBoolean, OrangInteger, OrangString, PartialBuiltinFunction,
-                PartialFunction, Undefined {
+                permits Array, BuiltinFunction, Function, Nothing, OrangBoolean, OrangInteger, OrangString, PartialBuiltinFunction, PartialFunction, Undefined {
         String typeName();
         String stringify();
 
diff --git a/orang/src/main/resources/lv/enes/orang/prelude.orang b/orang/src/main/resources/lv/enes/orang/prelude.orang
index d29eef3..5b1d2d1 100644
--- a/orang/src/main/resources/lv/enes/orang/prelude.orang
+++ b/orang/src/main/resources/lv/enes/orang/prelude.orang
@@ -4,10 +4,10 @@ def len arrayOrString = __builtin_len arrayOrString
 def parseInt stringOrInt = __builtin_parseInt stringOrInt
 def print anything = __builtin_print anything
 def randInt min max = __builtin_randInt min max
-def readLn _ = __builtin_readLn ()
+def readLn () = __builtin_readLn ()
 
 # standard library
-def readInt _ = parseInt (readLn ())
+def readInt () = parseInt (readLn ())
 def printLn x = do print x; print "\n"; x end
 
 # repl intro :)