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Ask the right questions to secure the right APL talent among an increasingly shrinking pool of talent.
APL (A Programming Language) is a high-level, interactive programming language known for its distinctive array processing capabilities. The language was developed in the 1960s by Kenneth E. Iverson while at IBM, as detailed in his book "A Programming Language" (source: Iverson K.E., Wiley, 1962). APL is unique due to its use of non-alphanumeric symbols for both arithmetic and data manipulation operations. Its influence can be seen in later array languages such as J and K (source: "The J Programming Language", Roger Hui). Despite its age, APL continues to be used today, especially in areas involving complex data analysis or mathematical modeling (source: "The Past, Present and Future of APL", SIGAPL conference).
The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.
The rho function in APL has two main uses. It can be used to reshape an array, changing its dimensions while keeping its elements, or it can be used to find the shape of an array, returning a vector that represents the array's dimensions.
The iota function in APL is used to generate a vector of consecutive integers. For example, '?5' would generate the vector 1 2 3 4 5.
Scalar functions in APL operate element-wise on arrays, meaning they perform their operation on each element of the array individually. Non-scalar functions, on the other hand, can manipulate the array as a whole.
The basic data types in APL are numeric (including both integers and floating-point numbers), character (representing individual characters), and arrays (which can hold any combination of numeric and character data).
APL's array programming model is a paradigm where data is represented as arrays and operations are performed on these arrays as a whole rather than on individual elements. This allows for concise and expressive code.
The tech industry is always evolving, and a good developer should be willing to learn and adapt to stay relevant.
Previous experience with similar projects or tasks can indicate that the candidate is capable of handling the responsibilities of the position.
Understanding the tools and technologies used in your organization will allow the candidate to quickly adapt to the work environment.
An APL developer should be able to efficiently solve problems, as they will be required to develop and debug code.
Communication skills are important in a development team to ensure everyone understands the code and the problem-solving approach.
A deep understanding of APL is critical for the candidate to be able to solve complex problems and write efficient code.
The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.
A quicksort algorithm in APL can be implemented in a very concise way using the grade up function '?'. For example, if V is a vector, then 'V[?V]' would return a sorted version of V.
Explicit programming in APL involves writing out each step of a computation in detail, while tacit programming involves defining computations in terms of the transformations they perform on data, without specifying the data itself. Tacit programming can lead to more concise and expressive code.
The commute function in APL, represented by the symbol '~', has two main uses. It can be used to reverse the order of arguments to a dyadic function, or it can be used monadically to create a function that returns the set difference of its arguments.
Matrix multiplication in APL can be implemented using the inner product operator '.+'. For example, if A and B are matrices, then the expression 'A .+.× B' would compute the matrix product of A and B.
Monadic functions in APL are functions that take one argument, while dyadic functions take two arguments. The behavior of a function can change depending on whether it is used monadically or dyadically.
A skilled APL engineer should demonstrate strong problem-solving skills, deep understanding of APL programming language, and good communication abilities. Red flags include inability to explain complex concepts clearly, lack of practical experience with APL, and poor problem-solving strategies.
5 3 2 + 4 2 1?103 3??92 2??4+/1 2 3 4 52 2??4The final few interview questions for a APL candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.
Traditional functions in APL are defined using a header line and a set of control structures, while direct functions are defined using a single expression. Direct functions are more concise and easier to compose, but traditional functions are more flexible and can handle more complex control flow.
The branch function in APL, represented by the symbol '?', is used to control the flow of execution in a program. It can be used to jump to a specific line of code, or to exit a function or loop prematurely.
Errors in APL can be handled using the error guard function '?EA'. This function takes a string of APL code as its right argument and a value as its left argument. If the code produces an error, the function returns the left argument; otherwise, it returns the result of the code.
The execute function in APL, represented by the symbol '?', is used to evaluate a string of APL code, while the format function, represented by the symbol '?', is used to convert APL data into a string representation.
The enclose function in APL, represented by the symbol '?', is used to group elements of an array into a single element, while the disclose function, represented by the symbol '?', is used to separate a grouped element back into its constituent elements.
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