[].all? doesn't take a block?

Ruby
1

Anybody know what’s going on here?

[].all?
=> true

After 5 years of using ruby, it still
surprises me at times–shouldn’t that require a block? :slight_smile:
-roger-

2

Roger P. wrote in post #1005933:

Anybody know what’s going on here?

[].all?
=> true

After 5 years of using ruby, it still
surprises me at times–shouldn’t that require a block? :slight_smile:
-roger-

class Enumerable

enum.all? [{|obj| block } ] → true or false
…
…
If the block is not given, Ruby adds an implicit block of {|obj| obj}
(that is all? will return true only if none of the collection members
are false or nil.)

None of your collection members are false or nil, so all? returns true.

3

7stud – wrote in post #1006058:

Roger P. wrote in post #1005933:

Anybody know what’s going on here?

[].all?
=> true

After 5 years of using ruby, it still
surprises me at times–shouldn’t that require a block? :slight_smile:
-roger-

class Enumerable

enum.all? [{|obj| block } ] → true or false
…
…
If the block is not given, Ruby adds an implicit block of {|obj| obj}
(that is all? will return true only if none of the collection members
are false or nil.)

None of your collection members are false or nil, so all? returns true.

I think the result is counterintuitive.
[].none? also returns true.

4

Joey Z. wrote in post #1006108:

Anybody know what’s going on here?

[].all?
=> true

None of your collection members are false or nil, so all? returns true.

I think the result is counterintuitive.

Let’s check Haskell:

any (==4) [3, 4]
=> True
any (==4) []
=> False
all (==4) [3, 4]
=> False
all (==4) []
=> True