Louis Hjelmslev is well-known among many linguists for his model of semiotic communication mediums, including language. The application of this model, which divides certain aspects of language into a content plane and expression plane, is not limited to just natural language, however. Hjelmslev’s model can also be applied and used to discuss other mediums of semiotic communication, including computer programming languages.

A semiotic code’s content-continuum is defined at the most basic logical level, in this case the machine level. The content-continuum encompasses all that can possibly be expressed, or in this case calculated. Obviously the breadth of a the content-continuum is rather limited by the capabilities of the “speaker(s)” of said language. A language cannot adequately express objects if the logical mind of the speaker is unable to comprehend said objects. Computers, for example, are limited by the fact that they operate on a deceptively simple system of binary arithmetic and logic. While computer scientists have not yet explored the full spectrum of all that can be expressed through complex binary logic, it is certainly more difficult to express abstract thought (similar to our own) in a computing language due to the limited true-false nature of binary logic.

The content-form of a language organizes the way in which communication takes place. Unlike the content-continuum, it defines not what it is possible possible to express, but how one thinks about what it is possible to express. One particularly interesting concept to consider when discussing the content-form of programming languages is that of object orientation versus proceduralism. Most modern languages are either object oriented or procedural in design. The se language design concepts entail more than simple differences in syntax; rather they are fundamentally different ways of evaluating and expressing programatic concepts. An object oriented language’s content-form is radically different from that of a procedural language, since its data and logic is manipulated through one or more “objects,” something of which procedural languages have no comprehension nor syntax with which to express it. Likewise, on a higher hierarchical level, these two very different categories of programming languages require highly divergent expression-form sub-planes.

Programmers are writers of a high level language which the “mind,” in this case a computer, is able to parse and understand. Generally speaking, programmers do not dabble in pure binary programming. They typically write instructions in a language which is a comfortable middle-ground between the binary logic of computers, and the infinitely complicated nature of our own content-continuum. It could be said the programmers primarily concern themselves with the expression plane of Hjelmslev’s semiotic model. As such, they are limited by the capabilities of the expression-form of said programming languages. The expression-form of a language, defines what can be expressed by a language. A computer language’s expression-form would consist of the rules of the language; it would include things like language syntax, methods, organization, etc.

Closely related to the expression-form sub-plane of Hjelmslev’s model is the content-substance sub-plane. This sub-plane is what gives various elements of the expression-form sub-plane meaning. It gives them denotations beyond a simple series of simple forms. The computer is able, through the content-substance sub-plane, to interpret a program not as a series of mere symbols, but as a series of executable instructions. This sub-plane enables a computer to “read” a program and do.

A finished program, a list of instructions conforming to the limits set forth by the expression-form of a language, would be placed on the expression-substance sub-plane of Hjelmslev’s semiotic model. This sub-plane is the tangible expression of ideas through the expression-form of a language. In the context of a written language, this might include a book. A program, like a book, uses the standard definition of a specific semiotic communication medium to express concepts in a tangible form, in this case a series of abstracted procedures which have been reduced to mathematical operations.

Natural, spoken and written languages tend to have closely linked, co-dependent content and expression planes. These expression planes allow for double-articulation, in that by breaking down a phrase into its simplest, otherwise insignificant, morphemes, content and meaning can be derived. Despite the close link between the two planes, there is still generally a small amount of autonomy between the planes. Computer languages content and expression planes have significantly less autonomy. In parsing a high-level language, a computer systematically derives all meaning (procedural instructions) from the expression plane. There is no disconnect between the two planes, whatsoever. We are limited by the lack of true understanding by the computer of all that can be abstractly described using the expression-form sub-plane. Despite the fact that programmers are able to discern meaning in code beyond what is specifically written, computers process only the denoted processes defined in the code with no real understanding of external connotations (which are learned by sentient minds through exposure.)

Programming languages, as complex semiotic codes with double articulation, can be broken down and analyzed using Hjelmslev's model. Perhaps however, computer languages and natural language will eventually converge enough that there will be little point in discussing the two separately.

Badir, Sémir. “The Semiotic Hierarchy.” Signo. 2006. Web. <http://www.signosemio.com/Hjelmslev/a_hier.asp>.

Eco, Umberto. The Search for the Perfect Language. Trans. James Fentress. Malden, MA: Blackwell, 1995. Print.

Hjelmslev, Louis. Prolegomena to a Theory of Language. Madison, WI: University of Wisconsin Press, 1943. Print.