@lang:count

Count the elements of an array that satisfy the predicate.

Returns: number

Syntax

@lang:count(arr fn)

Arguments

Name	Type	Description
arr	array	Source array
fn	helper	Predicate helper returning bool

Examples

load lang [@count]

def @isBig "$n: number -> bool" @bool($n > 2)

# 2
print @count([1 2 3 4] @isBig)

See Also

• @filter: keep the matching elements
• @any: true if at least one matches
• @all: true if all match
• @len: the number of elements

On-chain face (@count!)

Count the elements for which a named boolean callback returns true. Empty arrays count 0. Callbacks support composed helpers and ABI calls over typed single-word or multiword elements.

Examples

load lang

set $vault 0x44fA8E6f47987339850636F88629646662444217
set $token 0x6B175474E89094C44Da98b954EedeAC495271d0F

# At least two caps are 100 or more
def @ge100! "$x: number -> bool" @bool!($x >= 100)
assert @count!($vault::!{caps()(uint256[])} @ge100!) >= 2

# At least three holders have a balance of 1000 or more
def @funded! "$who: address -> bool" @bool!($token::!{balanceOf(address)(uint256) $who} >= 1000)
assert @count!($vault::!{holders()(address[])} @funded!) >= 3

Notes

• Same result as @len!(@filter!(...)), without building the filtered array.
• A predicate that compares one call over the element with a value, such as a balance against a minimum, costs one call per element. The value may be a call of its own: it is read once, not once per element.