Introducing Essence#: A Smalltalk-based Language for .NET

Essence# is described as a .NET-compatible language built by Alan Lovejoy as a Smalltalk-based superset for a specific trading use case. The language was created so non-programmer trading partners could write trading plan scripts, and it is designed to be easier for them than C# or EasyLanguage.

The article explains that Essence# is dynamically typed, strongly typed at run time, and built on the DLR. It emphasizes interoperability with other .NET languages, where Essence# objects can be called from foreign code and can also work with foreign types. It also highlights several design ideas that differ from C#, including namespaces as objects, object state architectures, and traits as a way to compose behavior.

Reading notes

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• Essence# was built for trading financial markets, especially for writing trading plan scripts triggered by buy or sell signals.
• The language was created for trading partners who are not programmers and should not need to master computer science.
• Essence# is presented as easier for that use case than TradeStation’s EasyLanguage and much easier than C#.
• The language runs on top of the Dynamic Language Runtime and was implemented as a .NET language because NinjaTrader is implemented in C#.
• Essence# can be used with a Java or C# style, a Python style, or a Smalltalk style, depending on the use case.
• The design favors minimal syntax and assumes the programmer is competent.
• Essence# uses dynamic typing with no static type checking in the language syntax, while still enforcing type safety at run time.
• The DLR is used for code generation, parameters, closures, message sends, and interoperability with foreign objects.
• Essence# objects implement IDynamicMetaObjectProvider and can interact with other languages that use the DLR protocol.
• The compiler emits a DLR CallSite for every message send and resolves message sending at run time.
• Namespaces are actual objects, and code can store loose variables, constants, and functions in them.
• The main namespaces are Root, default, CLR, and Undeclared.
• Namespace entries can be Public, Local, or InHierarchy.
• The article introduces object state architecture as a way to describe classes by how their instances behave at runtime.
• It lists architectures such as Abstract, Stateless, NamedSlots, IndexedObjectSlots, and Indexed[Type]Slots.
• It also lists system architectures such as Message, Namespace, Pathname, Block, Method, Behavior, Class, Metaclass, BehavioralTrait, and HostSystemObject.
• Traits are presented as Essence#’s answer to multiple inheritance.
• Traits can be combined with +, with conflicting methods excluded, and can also be adjusted with - and @.
• Essence# is available on CodePlex under the Simplified BSD License.
• Alan Lovejoy is described as a discretionary trader and former software engineer with experience in trading and Smalltalk.