Revision as of 22:52, 15 January 2014 (view source) Kazinator (talk \| contribs) (→‎{{header\|TXR}}: Added.) ← Older edit		Revision as of 00:08, 16 January 2014 (view source) Kazinator (talk \| contribs) (→‎{{header\|TXR}}: Variant C.) Newer edit →
Line 1,566: Reduce with + operator over a lazily generated list. Variant AA1: limit the list generation inside the <code>gen</code> operator. <lang shtxr>txr -c '@(bind sum @[reduce-left + (let ((i 0)) (gen (< i 1000) (/ 1.0 (* (inc i) i)))) 0])' sum="1.64393456668156"</lang> ~~</lang>~~ Variant BA2: generate infinite list, but take only the first 1000 items using <code>[list-expr 0..999]</code>. <lang shtxr>txr -c '@(bind sum @[reduce-left + [(let ((i 0)) (gen t (/ 1.0 (* (inc i) i)))) 0..999] 0])' sum="1.64393456668156"</lang> ~~</lang>~~ Variant B: generate lazy integer range, and pump it through a series of function with the help of the <code>chain</code> functional combinator and the <code>op</code> partial evaluation/binding operator. <lang txr>txr -c '@(bind sum @[[chain range (op mapcar (op / 1.0 (* @1 @1))) (op reduce-left + @1 0)] 1 1000])' sum="1.64393456668156"</lang> =={{header\|UnixPipes}}==

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