8.12
2 list module
| (require syntax/list) | package: syntax-extension |
procedure
(stx-length stx) → (or/c integer? #f)
stx : syntax?
Get the length of syntax if it’s list-like syntax, or returns #f.
Examples:
> (stx-length #'(1 2 3)) 3
> (stx-length #'(a b (c d) e)) 4
> (stx-length #'a) #f
> (stx-length #'()) 0
procedure
(stx-length=? left right) → boolean?
left : syntax? right : syntax?
Compare the length of left and right is different, and notice if one of left or right is not list-like syntax, than the result is always #f.
Examples:
> (stx-length=? #'(1 2 3) #'(a b c)) #t
> (stx-length=? #'(1 2 3) #'()) #f
> (stx-length=? #'(1 2 3) #'a) #f
> (stx-length=? #'a #'b) #f
procedure
(stx-length<=? left right) → boolean?
left : syntax? right : syntax?
Just like stx-length=? but for <= relation.
Examples:
> (stx-length<=? #'(1) #'(a b c)) #t
> (stx-length<=? #'(1 2 3) #'()) #f
procedure
(stx-length>=? left right) → boolean?
left : syntax? right : syntax?
Just like stx-length=? but for >= relation.
Examples:
> (stx-length>=? #'(1) #'(a b c)) #f
> (stx-length>=? #'(1 2 3) #'()) #t