Continuations in Scheme are first-class objects. Scheme provides the procedure call-with-current-continuation (also known as call/cc) to capture the current continuation by packing it up as an escape procedure bound to a formal argument in a procedure provided by the programmer. (R5RS sec. 6.4)[4] First-class continuations enable the programmer to create non-local control constructs such as iterators, coroutines, and backtracking.

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Similar procedures are provided for input. R5RS Scheme provides the predicates input-port? and output-port?. For character input and output, write-char, read-char, peek-char and char-ready? are provided. For writing and reading Scheme expressions, Scheme provides read and write. On a read operation, the result returned is the end-of-file object if the input port has reached the end of the file, and this can be tested using the predicate eof-object?.

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R5RS resolves this confusion by specifying three procedures that return environments and providing a procedure eval that takes an s-expression and an environment and evaluates the expression in the environment provided. (R5RS sec. 6.5)[4] R6RS extends this by providing a procedure called environment by which the programmer can specify exactly which objects to import into the evaluation environment.

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Chez scheme is a notable example for individual type of implementation of Scheme, it was created by R. Kent Dybvig in 1985. Chez Scheme includes completely different implementation of Scheme, which could replace some of the functions of Racket. Chez scheme has a relatively different core part in distribution. As a result, the application of Chez scheme can make every Racket runs magically fast.[36]

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It is used for research, in fields of technology or social science. Research funding can split into commercial and non-commercial. Research and development departments of a corporation normally provide commercial research funding. Whereas, non-commercial research funding is obtained from charities, research councils, or government agencies.[4] Organisations that require such funding normally have to go through competitive selections. Only those that have the most potential would be chosen. Funding is vital in ensuring the sustainability of certain projects.

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You can’t change your funding goal once you’ve launched. But once that goal has been reached, some projects add incentives — like new features, colors, or gifts to backers — to hit even higher funding milestones. These stretch goals can work for some — but they can also be challenging. They’re a better idea when they improve the work (like adding more levels to a video game), instead of creating something entirely new. Here are some things to think about before adding stretch goals.

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