Def reduce(f;k;as) == Case of as; nil  k ; a.as'  f(a,reduce(f;k;as'))
Def (recursive)

is mentioned by

Def ForHdTl{A,f,k} h::t  as. g(h;t) == reduce(f;k;mapcons(h,t. g(h;t);as))	[for_hdtl]
Def For{T,op,id} x  as. f(x) == reduce(op;id;map(x:T. f(x);as))	[for]

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