f::fold1 (public)

 f::fold1 f xs

Defined in packages/acs-tcl/tcl/ad-functional-procs.tcl

Takes a binary function f and a list {x1 x2 x3 ...} and returns (...(f (f (f x1 x2) x3) x4)...). "fold1" behaves like "fold", but does not take a start element and does not work for empty lists. Examples: f::fold1 min [list 3 1 4 1 5 9 2 6] = 1 f::fold1 max [list 3 1 4 1 5 9 2 6] = 9

Parameters:

f (required)

xs (required)

See Also:

• fold1

Testcases:

functional_api

Source code:

    if { [null_p $xs] } {
        error "ERROR: fold1 is undefined for empty lists."
    } else {
        fold $f [head $xs] [tail $xs]
    }

XQL Not present:

Generic, PostgreSQL, Oracle