ppx_deriving_cmdliner

library ppx_deriving_cmdliner

module Ppx_deriving_cmdliner

module Ast_builder_default_loc


Compare the lengths of two lists. compare_lengths l1 l2
is equivalent to compare (length l1) (length l2)
, except that the computation stops after reaching the end of the shortest list.
Compare the length of a list to an integer. compare_length_with l len
is equivalent to compare (length l) len
, except that the computation stops after at most len
iterations on the list.
Return the n
th element of the given list. The first element (head of the list) is at position 0.
Return the n
th element of the given list. The first element (head of the list) is at position 0. Return None
if the list is too short.
init len f
is f 0; f 1; ...; f (len1)
, evaluated left to right.
Concatenate two lists. Same function as the infix operator @
. Not tailrecursive (length of the first argument). The @
operator is not tailrecursive either.
rev_append l1 l2
reverses l1
and concatenates it with l2
. This is equivalent to (
rev
l1) @ l2
, but rev_append
is tailrecursive and more efficient.
Concatenate a list of lists. The elements of the argument are all concatenated together (in the same order) to give the result. Not tailrecursive (length of the argument + length of the longest sublist).
Same as concat
. Not tailrecursive (length of the argument + length of the longest sublist).
Comparison
equal eq [a1; ...; an] [b1; ..; bm]
holds when the two input lists have the same length, and for each pair of elements ai
, bi
at the same position we have eq ai bi
.
Note: the eq
function may be called even if the lists have different length. If you know your equality function is costly, you may want to check compare_lengths
first.
compare cmp [a1; ...; an] [b1; ...; bm]
performs a lexicographic comparison of the two input lists, using the same 'a > 'a > int
interface as Stdlib.compare
:
a1 :: l1
is smaller thana2 :: l2
(negative result) ifa1
is smaller thana2
, or if they are equal (0 result) andl1
is smaller thanl2
 the empty list
[]
is strictly smaller than nonempty lists
Note: the cmp
function will be called even if the lists have different lengths.
Iterators
iter f [a1; ...; an]
applies function f
in turn to a1; ...; an
. It is equivalent to begin f a1; f a2; ...; f an; () end
.
Same as iter
, but the function is applied to the index of the element as first argument (counting from 0), and the element itself as second argument.
map f [a1; ...; an]
applies function f
to a1, ..., an
, and builds the list [f a1; ...; f an]
with the results returned by f
. Not tailrecursive.
Same as map
, but the function is applied to the index of the element as first argument (counting from 0), and the element itself as second argument. Not tailrecursive.
filter_map f l
applies f
to every element of l
, filters out the None
elements and returns the list of the arguments of the Some
elements.
fold_left_map
is a combination of fold_left
and map
that threads an accumulator through calls to f
.
fold_left f init [b1; ...; bn]
is f (... (f (f init b1) b2) ...) bn
.
fold_right f [a1; ...; an] init
is f a1 (f a2 (... (f an init) ...))
. Not tailrecursive.
Iterators on two lists
iter2 f [a1; ...; an] [b1; ...; bn]
calls in turn f a1 b1; ...; f an bn
.
map2 f [a1; ...; an] [b1; ...; bn]
is [f a1 b1; ...; f an bn]
.
fold_left2 f init [a1; ...; an] [b1; ...; bn]
is f (... (f (f init a1 b1) a2 b2) ...) an bn
.
fold_right2 f [a1; ...; an] [b1; ...; bn] init
is f a1 b1 (f a2 b2 (... (f an bn init) ...))
.
List scanning
for_all f [a1; ...; an]
checks if all elements of the list satisfy the predicate f
. That is, it returns (f a1) && (f a2) && ... && (f an)
for a nonempty list and true
if the list is empty.
exists f [a1; ...; an]
checks if at least one element of the list satisfies the predicate f
. That is, it returns (f a1)  (f a2)  ...  (f an)
for a nonempty list and false
if the list is empty.
Same as for_all
, but for a twoargument predicate.
Same as exists
, but for a twoargument predicate.
Same as mem
, but uses physical equality instead of structural equality to compare list elements.
List searching
find f l
returns the first element of the list l
that satisfies the predicate f
.
find f l
returns the first element of the list l
that satisfies the predicate f
. Returns None
if there is no value that satisfies f
in the list l
.
find_map f l
applies f
to the elements of l
in order, and returns the first result of the form Some v
, or None
if none exist.
filter f l
returns all the elements of the list l
that satisfy the predicate f
. The order of the elements in the input list is preserved.
find_all
is another name for filter
.
Same as filter
, but the predicate is applied to the index of the element as first argument (counting from 0), and the element itself as second argument.
partition f l
returns a pair of lists (l1, l2)
, where l1
is the list of all the elements of l
that satisfy the predicate f
, and l2
is the list of all the elements of l
that do not satisfy f
. The order of the elements in the input list is preserved.
val partition_map :
( 'a > ( 'b, 'c ) Either.t ) >
'a list >
'b list * 'c list
partition_map f l
returns a pair of lists (l1, l2)
such that, for each element x
of the input list l
:
 if
f x
isLeft y1
, theny1
is inl1
, and  if
f x
isRight y2
, theny2
is inl2
.
The output elements are included in l1
and l2
in the same relative order as the corresponding input elements in l
.
In particular, partition_map (fun x > if f x then Left x else Right x) l
is equivalent to partition f l
.
Association lists
assoc a l
returns the value associated with key a
in the list of pairs l
. That is, assoc a [ ...; (a,b); ...] = b
if (a,b)
is the leftmost binding of a
in list l
.
assoc_opt a l
returns the value associated with key a
in the list of pairs l
. That is, assoc_opt a [ ...; (a,b); ...] = Some b
if (a,b)
is the leftmost binding of a
in list l
. Returns None
if there is no value associated with a
in the list l
.
Same as assoc
, but uses physical equality instead of structural equality to compare keys.
Same as assoc_opt
, but uses physical equality instead of structural equality to compare keys.
Same as assoc
, but simply return true
if a binding exists, and false
if no bindings exist for the given key.
Same as mem_assoc
, but uses physical equality instead of structural equality to compare keys.
remove_assoc a l
returns the list of pairs l
without the first pair with key a
, if any. Not tailrecursive.
Same as remove_assoc
, but uses physical equality instead of structural equality to compare keys. Not tailrecursive.
Lists of pairs
Transform a list of pairs into a pair of lists: split [(a1,b1); ...; (an,bn)]
is ([a1; ...; an], [b1; ...; bn])
. Not tailrecursive.
Transform a pair of lists into a list of pairs: combine [a1; ...; an] [b1; ...; bn]
is [(a1,b1); ...; (an,bn)]
.
Sorting
Sort a list in increasing order according to a comparison function. The comparison function must return 0 if its arguments compare as equal, a positive integer if the first is greater, and a negative integer if the first is smaller (see Array.sort for a complete specification). For example, Stdlib.compare
is a suitable comparison function. The resulting list is sorted in increasing order. sort
is guaranteed to run in constant heap space (in addition to the size of the result list) and logarithmic stack space.
The current implementation uses Merge Sort. It runs in constant heap space and logarithmic stack space.
Same as sort
, but the sorting algorithm is guaranteed to be stable (i.e. elements that compare equal are kept in their original order).
The current implementation uses Merge Sort. It runs in constant heap space and logarithmic stack space.
Same as sort
or stable_sort
, whichever is faster on typical input.
Same as sort
, but also remove duplicates.
Merge two lists: Assuming that l1
and l2
are sorted according to the comparison function cmp
, merge cmp l1 l2
will return a sorted list containing all the elements of l1
and l2
. If several elements compare equal, the elements of l1
will be before the elements of l2
. Not tailrecursive (sum of the lengths of the arguments).
Lists and Sequences
val to_seq : 'a list > 'a Seq.t
Iterate on the list.
val of_seq : 'a Seq.t > 'a list
Create a list from a sequence.