Parse function bindings

AST.cs

@@ -40,8 +40,6 @@ public partial record Literal
 	}
 }
 
-public record Binding(Pattern Pattern, Expr Value);
-
 public partial record SimplePattern
 {
 	public override string ToString()
@@ -54,6 +52,16 @@ public partial record SimplePattern
 	}
 }
 
+public abstract record Binding(Expr Value);
+public record VarBinding(Pattern Pattern, Expr Value) : Binding(Value);
+public record FuncBinding(Name Name, SimplePattern[] Params, Expr Value) : Binding(Value)
+{
+	public override string ToString()
+	{
+		return $"FuncBinding {{ Name = {Name}, Params = {string.Join(", ", (IEnumerable<object?>)(this.Params))}, Value = {this.Value} }}";
+	}
+}
+
 public partial record Let
 {
 	public override string ToString()

Parser.cs

@@ -248,20 +248,53 @@ class Parser
 			return ifExpr();
 		}
 
-		// TODO Add function bindings.
 		List<Binding> bindings = new List<Binding>();
-		Pattern p = pattern();
-		consume(TokenType.Equal, "Expect '=' after pattern.");
-		bindings.Add(new(p, expression()));
+		bindings.Add(parseBinding());
 		while (match(TokenType.And))
 		{
-			p = pattern();
-			consume(TokenType.Equal, "Expect '=' after pattern.");
-			bindings.Add(new(p, expression()));
+			bindings.Add(parseBinding());
 		}
 		consume(TokenType.In, "Expect 'in' after let-bindings.");
 		Expr body = expression();
 		return new Let(bindings.ToArray(), body);
+
+		Binding parseBinding()
+		{
+			Pattern p = pattern();
+			switch (p)
+			{
+				case (SimplePattern(var funcName)) when funcName != null && match(TokenType.LParen):
+					List<SimplePattern> funcParams = new List<SimplePattern>();
+					while (!check(TokenType.RParen))
+					{
+						Name? paramName;
+						if (match(TokenType.Blank))
+						{
+							funcParams.Add(new(null));
+						}
+						else if ((paramName = name()) != null)
+						{
+							funcParams.Add(new(paramName));
+						}
+						else
+						{
+							throw error(peek(), "Expect identifier or '_' as function parameter.");
+						}
+						if (!match(TokenType.Comma))
+						{
+							break;
+						}
+					}
+					consume(TokenType.RParen, "Expect ')' at end of parameters.");
+					consume(TokenType.Equal, "Expect '=' after parameters.");
+					return new FuncBinding(funcName, funcParams.ToArray(), expression());
+				default:
+					consume(TokenType.Equal, "Expect '=' after pattern.");
+					return new VarBinding(p, expression());
+			}
+		}
+
+
 	}
 
 	private Expr ifExpr()
@@ -300,7 +333,7 @@ class Parser
 			Pattern pat = pattern();
 			consume(TokenType.DoubleArrow, "Expect '=>' after pattern.");
 			Expr value = expression();
-			return new(pat, value);
+			return new VarBinding(pat, value);
 		}
 	}
 
@@ -357,7 +390,7 @@ class Parser
 					break;
 				}
 			}
-			consume(TokenType.RParen, "Expect '(' after arguments.");
+			consume(TokenType.RParen, "Expect ')' after arguments.");
 			return new Call(expr, args.ToArray());
 		}