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The tail call doesn't have to appear lexically after all other statements in the source code; it is only important that the calling function return immediately after the tail call, returning the tail call's result if any, since the calling function is bypassed when the optimization is performed.
Consider the following MATLAB code: x = 0 : 999 ; % Create an array of numbers from 0 to 999 (range is inclusive) y = sin ( x ) + 4 ; % Take the sine of x (element-wise) and add 4 to each element The same syntax can be achieved in C++ by using function and operator overloading:
A similar idea can be used when the function must run in a different thread or on a different processor. The framework can execute the called function in a worker thread, then call the continuation function in the original thread with the worker's results. This is in Java 8 using the Swing UI framework:
Tail-call optimization A function call consumes stack space and involves some overhead related to parameter passing and flushing the instruction cache. Tail-recursive algorithms can be converted to iteration through a process called tail-recursion elimination or tail-call optimization. Deforestation (data structure fusion)
Note that tail call optimization in general (when the function called is not the same as the original function, as in tail-recursive calls) may be more difficult to implement than the special case of tail-recursive call optimization, and thus efficient implementation of mutual tail recursion may be absent from languages that only optimize tail ...
A compiler can use the results of escape analysis as a basis for optimizations: [1] Converting heap allocations to stack allocations. [2] If an object is allocated in a subroutine, and a pointer to the object never escapes, the object may be a candidate for stack allocation instead of heap allocation.
A simple tail recursive parser can be written much like a recursive descent parser. The typical algorithm for parsing a grammar like this using an abstract syntax tree is: Parse the next level of the grammar and get its output tree, designate it the first tree, F; While there is terminating token, T, that can be put as the parent of this node:
After a function's value is computed for that parameter or set of parameters, the result is stored in a lookup table that is indexed by the values of those parameters; the next time the function is called, the table is consulted to determine whether the result for that combination of parameter values is already available. If so, the stored ...