package containers

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Monadic Traverse
Parameters
Signature

package containers

containers
- CCArray
  - Infix
  - MONO_ARRAY
- CCArrayLabels
  - Infix
  - MONO_ARRAY
- CCAtomic
- CCBool
- CCByte_buffer
- CCByte_slice
- CCCanonical_sexp
  - Make
    
    Sexp
- CCChar
  - Infix
- CCEither
- CCEqual
  - Infix
- CCEqualLabels
  - Infix
- CCFloat
  - Infix
- CCFormat
  - ANSI_codes
  - Dump
  - Infix
- CCFun
  - Infix
  - Monad
    
    X
- CCHash
- CCHashtbl
  - Make
    
    X
  - Poly
  - S
- CCHeap
  - Make
    
    E
  - Make_from_compare
    
    E
  - PARTIAL_ORD
  - S
  - TOTAL_ORD
- CCIO
  - File
- CCInt
  - Infix
- CCInt32
  - Infix
- CCInt64
  - Infix
- CCList
  - Assoc
  - Infix
  - MONAD
  - Ref
  - Traverse
    
    M
- CCListLabels
  - Assoc
  - Infix
  - MONAD
  - Ref
  - Traverse
    
    M
- CCMap
  - Make
    
    O
  - S
- CCNativeint
  - Infix
- CCOpt
  - Infix
- CCOption
  - Infix
- CCOrd
  - Infix
- CCPair
- CCParse
  - Debug_
  - Error
  - Infix
  - Position
  - Slice
  - U
- CCRandom
- CCRef
- CCResult
  - Infix
  - MONAD
  - Traverse
    
    M
- CCSeq
  - Infix
  - MONAD
  - Traverse
    
    M
- CCSet
  - Make
    
    O
  - S
- CCSexp
  - Decoder
  - Make
    
    Decoder
    
    Sexp
- CCSexp_intf
  - BASIC_SEXP
  - S
    
    Decoder
  - S0
  - SEXP
- CCSexp_lex
- CCString
  - Find
  - Infix
  - Split
- CCStringLabels
  - Find
  - Infix
  - Split
- CCUnit
- CCUtf8_string
- CCVector
- Containers
  - Hashtbl
    
    HashedType
    
    MakeSeeded
    
    H
    
    S
    
    SeededHashedType
    
    SeededS
- ContainersLabels
  - Hashtbl
    
    HashedType
    
    MakeSeeded
    
    H
    
    S
    
    SeededHashedType
    
    SeededS
containers.bencode
- Containers_bencode
  - Decode
  - Encode
  - Str_map
containers.cbor
- Containers_cbor
containers.codegen
- Containers_codegen
  - Bitfield
  - Code
containers.monomorphic
- CCMonomorphic
containers.pp
- Containers_pp
  - Char
  - Dump
  - Ext
  - Flatten
  - Infix
  - Out
  - Pretty
  - Term_color
containers.pvec
- Containers_pvec
containers.scc
- Containers_scc
  - ARG
    
    Node_tbl
  - Make
    
    A
    
    Node_tbl
  - S
    
    A
    
    Node_tbl
containers.top
- Containers_top
containers.unix
- CCUnix
  - Infix

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Monadic Traverse

This allows the traversal of a 'a t list where _ t is also a monad.

For example, a 'a option list will be traversed by extracting a value from each option, returning Some [x1;…;x_n]; but if one of the option is None then the whole result is None.

Another example is with result: ('a, 'err) result list can be transformed into ('a list, 'err) result by returning the first error, or Ok [x1; …; xn] if all the elements were successful.

This describes the behavior of sequence_m; map_m is a combination of map and sequence_m; map_m_par is like map_m but useful for some pseudo monads like Lwt.

Parameters

module M : MONAD

Signature

val sequence_m : 'a M.t t -> 'a t M.t

Traverse the list of monadic values using M.(>>=), re-combining elements with (::). See the documentation of the Traverse functor itself.

val fold_m : ('b -> 'a -> 'b M.t) -> 'b -> 'a t -> 'b M.t

Fold a function with a monadic effect through a list.

val map_m : ('a -> 'b M.t) -> 'a t -> 'b t M.t

Combination of map and sequence_m.

val map_m_par : ('a -> 'b M.t) -> 'a t -> 'b t M.t

map_m_par f (x :: l) is like map_m but f x and f l are evaluated "in parallel" before combining their result (for instance in Lwt).

Basically, when encoutering x :: tl, this computes f x and map_m_par f tl, and only then is M.(>>=) used to combine the two results into a new list.