9 Sep
2012
9 Sep
'12
11:27 p.m.
On Fri, Sep 7, 2012 at 8:37 PM, Stephen Tetley
For foldr see Olivier Danvy and Michael Spivey's "On Barron and Strachey’s Cartesian Product Function" crediting a discovery to David Barron and Christopher Strachey.
That gives the date as 1966. APL had the fold operator -- called 'reduce' in APL terminology and notated with a slash '/' -- from around 1960 http://www.softwarepreservation.org/projects/apl/book/APROGRAMMING%20LANGUAG... is the 1962 book. Apl as a notation had existed some time before that.