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Overview<\/h4>\n
We claim that Scade One bridges the gap between model-based design and traditional programming<\/em>, but you might be wondering what it means. Here’s what we will show you in the rest of this blog. In a nutshell:<\/p>\n Modeling in Scade One is based on a domain-specific programming language called Swan, designed for real-time safe and reliable embedded software. This language builds on decades of research in the field of synchronous languages<\/a> (including the academic language Lustre) and the legacy of successive Scade language versions (up to Scade 6, used in SCADE Suite).<\/p>\n What are the benefits of this approach?<\/p>\n There are two ways to describe models using Swan:<\/p>\n \n Using diagrams<\/em> : the model is made of block diagrams that can be mixed with state machines. Block diagrams are a standard notation, very often used by control engineers for control law design.<\/p>\n <\/p>\n Using text<\/em> : an operator can be defined completely as text, like a function in a textual programming language.<\/p>\n Text and diagrams can be mixed: textual expressions or textual blocks can be put anywhere in a block diagram. You can decide to use either textual notation or block diagram notation (or both!), based on your preferences. For instance, diagrams are great to view the states and transitions of a state machine, while text can be more readable for complex arithmetic expressions.<\/p>\n Note that there is just one language. Any model can be described using diagrams or text. The serialization format is the same for textual and diagrammatic models.<\/p>\n \n All activities, from design to debugging to verification activities, can be performed for graphical and textual models. The modeler provides dedicated features for each approach:<\/p>\n Whether you are a control or systems engineer, familiar with model-based simulation tools, or a software engineer, used to Integrated Development Environments (IDEs), you will immediately feel at home with Scade One. Take a look at the first blog in this series<\/a> to learn more about Scade One’s new UI\/UX.<\/p>\n Swan is an evolution of Scade 6<\/a>, the language used in SCADE Suite<\/a> . Swan improves on Scade 6, but also extends it with new features to answer the challenges and objectives of a modern modeling and programming tool.<\/p>\n A very common drawback of visual programming languages is that diagrams can become messy visual spaghetti<\/em> .<\/p>\n <\/p>\n Me trying to explain my spaghetti “prototype” #UE4<\/a> blueprint code to literally anyone. pic.twitter.com\/GCeE6D5Yic<\/a><\/p>\n \u2014 Holomento (@HolomentoGame) May 20, 2020<\/a>\n<\/p><\/blockquote>\n Swan introduces the notion of groups, to simplify and declutter block diagrams. Groups allow one wire or variable to represent multiple flows:<\/p>\n \n Like Scade 6, Swan takes inspiration from programming language best practices and combines them with the model-based approach. For instance, Scade 6 allows the creation of reusable, generic libraries. Swan goes further by introducing the concept of interfaces, inspired from Ada<\/a>, that allow separation of the interface of a module from its implementation. This is particularly useful during early architectural design phases. Interfaces can also be used to control the visibility of declarations in a module. This can look very standard for a software engineer, but it is not usually found in other model-based tools.<\/p>\n \n Swan allows you to manipulate rich data types and data structures. On top of the arrays and structures already available in Scade 6, Swan supports the definition of variants (a.k.a. tagged unions). A variant can be used to store values of different types in the same flow or data structure.<\/p>\n <\/p>\n \n Swan also introduces a new for-loop-like construct to design iterative models, more intuitive than the iterators in Scade 6. This new construct can be used for arrays or matrix computations, like the matrix multiplication shown below, or for traversing data structures.<\/p>\n \n <\/p>\n Put together, these new constructs allow creating and manipulating complex data structures. This sets Swan aside from other model-based tools, and closer to the power and expressiveness of a general-purpose programming language. This means that you will be using Scade One, with all the associated benefits of reduced development time, for more applications than just traditional control applications.<\/p>\n In this blog, we’ve demonstrated how Scade One provides the best of both model-based and programming, resulting in a tool and language usable by both control\/systems and software engineers. We could only scratch the surface of Swan, so stay tuned for more deep dives into the new constructs of Swan and concrete examples.<\/p>\n In the next blog, we’ll discuss how Scade One integrates in a Model-Based Systems Engineering (MBSE) process.<\/p>\n Next in this series is Part 3<\/a>.<\/p>\n\n
Swan, a domain-specific language for embedded software<\/h4>\n
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One language, two notations<\/h4>\n
![](\"https:\/\/innovationspace.ansys.com\/knowledge\/wp-content\/uploads\/sites\/4\/2024\/01\/scade-002-block-diagram.png\")
\n<\/p>\n<\/span>let<\/span> y =<\/span> x +<\/span> 1<\/span>;\n<\/pre>\n<\/div>\n![](\"https:\/\/innovationspace.ansys.com\/knowledge\/wp-content\/uploads\/sites\/4\/2024\/01\/scade-002-diagrams-and-text.png\")
\nUsing diagrams, text or both in Scade One<\/em>\n<\/p>\n\n
Swan’s key features<\/h4>\n
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![](\"\/knowledge\/wp-content\/uploads\/sites\/4\/2024\/01\/scade-002-holomento-tweet.jpg\")
<\/p>\n![](\"https:\/\/innovationspace.ansys.com\/knowledge\/wp-content\/uploads\/sites\/4\/2024\/01\/scade-002-groups.png\")
\nThe same model without groups (left, in SCADE Suite) and with groups (right, in Scade One)<\/em>\n<\/p>\n![](\"https:\/\/innovationspace.ansys.com\/knowledge\/wp-content\/uploads\/sites\/4\/2024\/01\/scade-002-interfaces.png\")
\nUsing interfaces for a modular design<\/em>\n<\/p>\n<\/span>type<\/span> cartesian =<\/span> {x: float32<\/span>, y: float32<\/span>}\ntype<\/span> polar =<\/span> {rho: float32<\/span>, theta: float32<\/span>}\ntype<\/span> coord =<\/span> Cartesian {cart} | Polar {polar}\n<\/pre>\n<\/div>\n![](\"https:\/\/innovationspace.ansys.com\/knowledge\/wp-content\/uploads\/sites\/4\/2024\/01\/scade-002-variants.png\")
\nDeclaring (top) and using (bottom) variants<\/em>\n<\/p>\n![](\"https:\/\/innovationspace.ansys.com\/knowledge\/wp-content\/uploads\/sites\/4\/2024\/01\/scade-002-forward.png\")
\nMatrix multiplication using the new loop-like construct, using diagram notation<\/em>\n<\/p>\n<\/span>C =<\/span> forward<\/span> <‍<‍P‍>‍> with<\/span> <‍<‍i‍>‍> <‍<‍M‍>‍> with<\/span> <‍<‍j‍>‍>\n let<\/span> Cij =<\/span> forward<\/span> <‍<‍N‍>‍> with<\/span> <‍<‍k‍>‍>\n let<\/span> sum =<\/span> last<\/span> 'sum +<\/span> A[i][k] *<\/span> B [k][j];\n returns<\/span> (sum: last<\/span> =<\/span> 0<\/span>);\nreturns<\/span> ([[ Cij ]]); \n<\/pre>\n<\/div>\nStay tuned!<\/h4>\n
About the author<\/h4>\n
![](\"https:\/\/innovationspace.ansys.com\/knowledge\/wp-content\/uploads\/sites\/4\/2026\/08\/scade-cpasteur.png\")
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