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Hope is a small functional programming language developed in the 1970s at Edinburgh University.〔Burstall R.M, MacQueen D.B, Sannella D.T. (1980) ''Hope: An Experimental Applicative Language''. Conference Record of the 1980 LISP Conference, Stanford University, pp. 136-143.〕〔 R.M. Burstall. Design considerations for a functional programming language. Invited paper, Proc. Infotech State of the Art Conf. “The Software Revolution”, Copenhagen, 45–57 (1977)〕〔 〕〔 〕〔 〕 It predates Miranda and Haskell and is contemporaneous with ML (also developed at Edinburgh). Hope was derived from NPL, 〔 a simple functional language developed by Burstall and Darlington in their work on program transformation.〔 R.M. Burstall and J. Darlington. A transformation system for developing recursive programs. Journal of the Association for Computing Machinery, 24(1):44–67 (1977)〕 NPL was, in turn, derived from Kleene Recursion Equations. NPL and Hope are notable for being the first languages with call-by-pattern evaluation and algebraic data types. SNOBOL is even older, and its 'patterns' may qualify as a hybrid between call-by-pattern and regular expression matching. Hope is an important language in the development of functional programming. Hope was named for Sir Thomas Hope (c. 1681–1771), a Scottish agricultural reformer, after whom ''Hope Park Square'' in Edinburgh, the location of the Department of Artificial Intelligence at the time of the development of Hope, was also named. A factorial program in Hope is dec fact : num -> num; --- fact 0 <= 1; --- fact n <= n *fact(n-1); Unlike in Haskell, changing the order of the clauses would not change the meaning of the program, because Hope's pattern matching always favors more specific patterns over less specific ones. Another way in which Hope differs from Haskell and is that explicit type declarations in Hope are required: there is no option to use a type-inference algorithm in Hope. The first implementation of Hope was strict, but since that one there have been lazy versions and strict versions with lazy constructors (the language described in 〔 has a lazy constructor for lists only). ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hope (programming language)」の詳細全文を読む スポンサード リンク
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