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Reference · stzList

Reduce()

Reduce(): 0-arg auto-concat / auto-sum. - All-string items: concatenate. - All-number items: sum. - Mixed: concatenate stringified items.

Basic examples (1)

Softanza
# Reduce() of [1,2,3,4] is 10 (numeric sum)
? Q([1,2,3,4]).Reduce()
# ReduceXT('@accumulator + @item', 0) on [1..4] is 10
? Q([1,2,3,4]).ReduceXT("@accumulator + @item", 0)
# ReduceXT with init 100 is 110
? Q([1,2,3,4]).ReduceXT("@accumulator + @item", 100)
# ReduceNoInit('@accumulator * @item') on [1..4] is 24
? Q([1,2,3,4]).ReduceNoInit("@accumulator * @item")
Output
10
10
110
24

run on 2026-10-02 04:22 inside the library at commit 0e72e2e2c; taken from 00_list_narrated.ring(opens in a new tab)

The extensions of this method

Each extension, and whether it exists for this method; an extension that exists combines with the others (FindSTCS).

Extension
Exists
What it adds · The names
Q
no
does what the method does, then returns the object, so the call can be chained
QQ
no
chains on the next, more specific type of object (the Q ladder)
QQQ
no
chains on the most specific type of object (the Q ladder)
QRT
no
returns the result as an object of the requested type
CS
no
takes a case-sensitivity flag
ST
no
takes the position to start from (StartingAt)
IB
no
takes bounds that are included (IncludingBounds)
XT
yes
the extended form: more parameters than the base method · ReduceXT
XTT
no
yet another extension: a further extended form, after XT
Z
no
includes the position in what it returns
ZZ
no
returns positions as sections, [start, end]
W
no
selects by a condition
WF
no
selects by a condition, with the expressive keywords (@NextItem, @PreviousItem...)
D
no
takes a direction, forward or backward (Directional)
F
no
takes a function (the condition or the update is given as a function); the forms document also uses F for the future form, which defers the action
Many
no
works on a collection of items instead of one (the plural form)
Except
no
takes exceptions, what to leave out (the exceptional form)
U
no
returns the result without duplication

Every example is a test file of the library, run inside the library for this page; only those whose output kept every promise their file wrote are shown.

See also