Stdlib.Seq · ocaml-base-compiler 4.12.1

ocaml-base-compiler

Official release 4.12.1

Version

IN THIS PACKAGE

library bigarray
- module Bigarray
  - module Array0
  - module Array1
  - module Array2
  - module Array3
  - module Genarray
library dynlink
- module Dynlink
library ocamlbytecomp
- module Bytegen
- module Bytelibrarian
- module Bytelink
- module Bytepackager
- module Compile
- module Emitcode
- module Errors
- module Instruct
- module Maindriver
- module Printinstr
library ocamlcommon
- module Arg_helper
  - module Make
    
    argument 1-S
    
    module Key
    
    module Map
    
    module Value
- module Ast_helper
  - module Attr
  - module Cf
  - module Ci
  - module Cl
  - module Const
  - module Csig
  - module Cstr
  - module Ctf
  - module Cty
  - module Exp
  - module Incl
  - module Mb
  - module Md
  - module Mod
  - module Ms
  - module Mtd
  - module Mty
  - module Of
  - module Opn
  - module Pat
  - module Rf
  - module Sig
  - module Str
  - module Te
  - module Typ
  - module Type
  - module Val
  - module Vb
- module Ast_invariants
- module Ast_iterator
- module Ast_mapper
- module Attr_helper
- module Binutils
- module Btype
  - module For_copy
  - module TypeHash
  - module TypeMap
  - module TypeSet
- module Build_path_prefix_map
- module Builtin_attributes
- module Bytesections
- module CamlinternalMenhirLib
  - module Convert
    
    module Simplified
  - module Engine
    
    module Make
    
    argument 1-T
    
    module Log
  - module EngineTypes
    
    module type ENGINE
    
    module type INCREMENTAL_ENGINE_START
    
    module type MONOLITHIC_ENGINE
    
    module type TABLE
    
    module Log
  - module ErrorReports
  - module General
  - module IncrementalEngine
    
    module type EVERYTHING
    
    module type INCREMENTAL_ENGINE
    
    module type INSPECTION
    
    module type SYMBOLS
  - module InfiniteArray
  - module InspectionTableFormat
    
    module type TABLES
  - module InspectionTableInterpreter
    
    module Make
    
    argument 1-TT
    
    argument 2-IT
    
    argument 3-ET
    
    module Log
    
    argument 4-E
    
    module Symbols
    
    argument 1-T
  - module LinearizedArray
  - module PackedIntArray
  - module Printers
    
    module Make
    
    argument 1-I
    
    argument 2-User
  - module RowDisplacement
  - module StaticVersion
  - module TableFormat
    
    module type TABLES
  - module TableInterpreter
    
    module MakeEngineTable
    
    argument 1-T
    
    module Log
- module Ccomp
- module Clflags
  - module Compiler_pass
  - module Float_arg_helper
  - module Int_arg_helper
- module Cmi_format
- module Cmt2annot
- module Cmt_format
- module Compenv
- module Compile_common
- module Compmisc
- module Config
- module Consistbl
  - module Make
    
    argument 1-Module_name
    
    module Map
    
    module Set
    
    module Tbl
- module Ctype
  - module TypePairs
  - module Unification_trace
- module Datarepr
- module Debuginfo
  - module Scoped_location
- module Depend
- module Dll
- module Docstrings
  - module WithMenhir
- module Domainstate
- module Env
- module Envaux
- module Ident
  - module Map
  - module Set
  - module T
  - module Tbl
- module Identifiable
  - module Make
    
    argument 1-T
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module type Map
    
    module T
  - module Pair
    
    argument 1-A
    
    argument 2-B
  - module type S
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module type Set
    
    module T
  - module type Tbl
    
    module T
  - module type Thing
- module Includeclass
- module Includecore
- module Includemod
- module Int_replace_polymorphic_compare
- module Lambda
- module Lexer
- module Load_path
  - module Dir
- module Local_store
- module Location
- module Longident
- module Main_args
  - module type Arg_list
  - module type Bytecomp_options
  - module type Bytetop_options
  - module type Common_options
  - module type Compiler_options
  - module type Core_options
  - module Default
    
    module Main
    
    module Odoc_args
    
    module Optmain
    
    module Opttopmain
    
    module Topmain
  - module Make_bytecomp_options
    
    argument 1-_
  - module Make_bytetop_options
    
    argument 1-_
  - module Make_ocamldoc_options
    
    argument 1-_
  - module Make_optcomp_options
    
    argument 1-_
  - module Make_opttop_options
    
    argument 1-_
  - module type Ocamldoc_options
  - module type Optcommon_options
  - module type Optcomp_options
  - module type Opttop_options
  - module type Toplevel_options
- module Makedepend
- module Matching
- module Meta
- module Misc
  - module Color
  - module EnvLazy
  - module Error_style
  - module Int_literal_converter
  - module LongString
  - module Magic_number
  - module Stdlib
    
    module Array
    
    module List
    
    module Option
    
    module String
    
    module Map
    
    module Set
    
    module Tbl
- module Mtype
- module Numbers
  - module Float
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module Int
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module Int16
  - module Int8
- module Opcodes
- module Oprint
- module Parmatch
  - module Compat
    
    argument 1-_
- module Parse
- module Parser
  - module Incremental
  - module MenhirInterpreter
- module Path
  - module Map
  - module Set
- module Patterns
  - module General
  - module Half_simple
  - module Head
  - module Non_empty_row
  - module Simple
- module Persistent_env
  - module Consistbl
  - module Persistent_signature
- module Pparse
- module Pprintast
- module Predef
- module Primitive
- module Printast
- module Printlambda
- module Printpat
- module Printtyp
  - module Conflicts
  - module Naming_context
  - module Out_name
- module Printtyped
- module Profile
- module Rec_check
- module Runtimedef
- module Simplif
- module Strongly_connected_components
  - module Make
    
    argument 1-Id
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module type S
    
    module Id
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
- module Stypes
- module Subst
- module Switch
  - module CtxStore
    
    argument 1-A
  - module type CtxStored
  - module Make
    
    argument 1-Arg
  - module type S
  - module Store
    
    argument 1-A
  - module type Stored
- module Symtable
- module Syntaxerr
- module Targetint
- module Tast_iterator
- module Tast_mapper
- module Terminfo
- module Translattribute
- module Translclass
- module Translcore
- module Translmod
- module Translobj
- module Translprim
- module Type_immediacy
  - module Violation
- module Typeclass
- module Typecore
  - module Datatype_kind
- module Typedecl
- module Typedecl_immediacy
- module Typedecl_properties
- module Typedecl_separability
- module Typedecl_unboxed
- module Typedecl_variance
- module Typedtree
- module Typemod
  - module Sig_component_kind
  - module Signature_names
- module Typeopt
- module Types
  - module Concr
  - module Meths
  - module Separability
  - module TypeOps
  - module Uid
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module Variance
  - module Vars
- module Typetexp
- module Untypeast
- module Warnings
library ocamlmiddleend
- module Alias_analysis
- module Allocated_const
- module Augment_specialised_args
  - module Definition
  - module Make
    
    argument 1-_
  - module type S
  - module What_to_specialise
- module Backend_var
  - module Provenance
  - module With_provenance
- module Build_export_info
- module Clambda
- module Clambda_primitives
- module Closure
- module Closure_conversion
- module Closure_conversion_aux
  - module Env
  - module Function_decls
    
    module Function_decl
- module Closure_element
  - module Map
  - module Set
  - module T
  - module Tbl
- module Closure_id
  - module Map
  - module Set
  - module T
  - module Tbl
- module Closure_middle_end
- module Closure_offsets
- module Closure_origin
  - module Map
  - module Set
  - module T
  - module Tbl
- module Compilation_unit
  - module Map
  - module Set
  - module T
  - module Tbl
- module Compilenv
- module Convert_primitives
- module Effect_analysis
- module Export_id
  - module Map
  - module Set
  - module T
  - module Tbl
- module Export_info
- module Export_info_for_pack
- module Extract_projections
- module Find_recursive_functions
- module Flambda
  - module Constant_defining_value
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module With_free_variables
- module Flambda_invariants
- module Flambda_iterators
- module Flambda_middle_end
- module Flambda_to_clambda
- module Flambda_utils
  - module Switch_storer
- module Freshening
  - module Project_var
- module Id_types
  - module type BaseId
  - module Id
  - module UnitId
    
    argument 1-_
    
    argument 2-Compilation_unit
    
    module Compilation_unit
- module Import_approx
- module Inconstant_idents
- module Initialize_symbol_to_let_symbol
- module Inline_and_simplify
- module Inline_and_simplify_aux
  - module Env
  - module Result
- module Inlining_cost
  - module Benefit
  - module Threshold
  - module Whether_sufficient_benefit
- module Inlining_decision
- module Inlining_stats
  - module Closure_stack
- module Inlining_stats_types
  - module Decision
  - module Inlined
  - module Not_inlined
  - module Not_specialised
  - module Prevented
  - module Specialised
- module Inlining_transforms
- module Internal_variable_names
- module Invariant_params
- module Lift_code
- module Lift_constants
- module Lift_let_to_initialize_symbol
- module Linkage_name
  - module Map
  - module Set
  - module T
  - module Tbl
- module Mutable_variable
  - module Map
  - module Set
  - module T
  - module Tbl
- module Parameter
  - module List
  - module Map
  - module Set
  - module T
  - module Tbl
- module Pass_wrapper
- module Printclambda
- module Printclambda_primitives
- module Projection
  - module Map
  - module Set
  - module T
  - module Tbl
- module Ref_to_variables
- module Remove_free_vars_equal_to_args
- module Remove_unused_arguments
- module Remove_unused_closure_vars
- module Remove_unused_program_constructs
- module Semantics_of_primitives
- module Set_of_closures_id
  - module Map
  - module Set
  - module T
  - module Tbl
- module Set_of_closures_origin
  - module Map
  - module Set
  - module T
  - module Tbl
- module Share_constants
- module Simple_value_approx
- module Simplify_boxed_integer_ops
  - module Simplify_boxed_int32
  - module Simplify_boxed_int64
  - module Simplify_boxed_nativeint
- module Simplify_common
- module Simplify_primitives
- module Static_exception
  - module Map
  - module Set
  - module T
  - module Tbl
- module Symbol
  - module Map
  - module Set
  - module T
  - module Tbl
- module Tag
  - module Map
  - module Set
  - module T
  - module Tbl
- module Traverse_for_exported_symbols
- module Un_anf
- module Unbox_closures
- module Unbox_free_vars_of_closures
- module Unbox_specialised_args
- module Var_within_closure
  - module Map
  - module Set
  - module T
  - module Tbl
- module Variable
  - module Map
  - module Pair
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module Set
  - module T
  - module Tbl
library ocamloptcomp
- module Afl_instrument
- module Alias_analysis
- module Allocated_const
- module Arch
- module Asmgen
- module Asmlibrarian
- module Asmlink
- module Asmpackager
- module Augment_specialised_args
  - module Definition
  - module Make
    
    argument 1-_
  - module type S
  - module What_to_specialise
- module Available_regs
- module Backend_var
  - module Provenance
  - module With_provenance
- module Branch_relaxation
  - module Make
    
    argument 1-T
    
    module Cond_branch
- module Branch_relaxation_intf
  - module type S
    
    module Cond_branch
- module Build_export_info
- module CSE
  - cse
- module CSEgen
  - cse_generic
- module Clambda
- module Clambda_primitives
- module Closure
- module Closure_conversion
- module Closure_conversion_aux
  - module Env
  - module Function_decls
    
    module Function_decl
- module Closure_element
  - module Map
  - module Set
  - module T
  - module Tbl
- module Closure_id
  - module Map
  - module Set
  - module T
  - module Tbl
- module Closure_middle_end
- module Closure_offsets
- module Closure_origin
  - module Map
  - module Set
  - module T
  - module Tbl
- module Cmm
- module Cmm_helpers
- module Cmmgen
- module Cmmgen_state
- module Coloring
- module Comballoc
- module Compilation_unit
  - module Map
  - module Set
  - module T
  - module Tbl
- module Compilenv
- module Compute_ranges
  - module Make
    
    argument 1-S
    
    module Index
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
    
    module Key
    
    module Map
    
    module Set
    
    module Range_info
    
    module Subrange_info
    
    module Subrange_state
    
    module Range
    
    module Subrange
- module Compute_ranges_intf
  - module type S
    
    module Index
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
    
    module Key
    
    module Map
    
    module Set
    
    module Range
    
    module Range_info
    
    module Subrange
    
    module Subrange_info
    
    module Subrange_state
  - module type S_functor
    
    module Index
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
    
    module Key
    
    module Map
    
    module Set
    
    module Range_info
    
    module Subrange_info
    
    module Subrange_state
  - module type S_range_info
  - module type S_subrange_info
  - module type S_subrange_state
- module Convert_primitives
- module Deadcode
- module Effect_analysis
- module Emit
- module Emitaux
- module Export_id
  - module Map
  - module Set
  - module T
  - module Tbl
- module Export_info
- module Export_info_for_pack
- module Extract_projections
- module Find_recursive_functions
- module Flambda
  - module Constant_defining_value
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module With_free_variables
- module Flambda_invariants
- module Flambda_iterators
- module Flambda_middle_end
- module Flambda_to_clambda
- module Flambda_utils
  - module Switch_storer
- module Freshening
  - module Project_var
- module Id_types
  - module type BaseId
  - module Id
  - module UnitId
    
    argument 1-_
    
    argument 2-Compilation_unit
    
    module Compilation_unit
- module Import_approx
- module Inconstant_idents
- module Initialize_symbol_to_let_symbol
- module Inline_and_simplify
- module Inline_and_simplify_aux
  - module Env
  - module Result
- module Inlining_cost
  - module Benefit
  - module Threshold
  - module Whether_sufficient_benefit
- module Inlining_decision
- module Inlining_stats
  - module Closure_stack
- module Inlining_stats_types
  - module Decision
  - module Inlined
  - module Not_inlined
  - module Not_specialised
  - module Prevented
  - module Specialised
- module Inlining_transforms
- module Interf
- module Internal_variable_names
- module Interval
- module Invariant_params
- module Lift_code
- module Lift_constants
- module Lift_let_to_initialize_symbol
- module Linear
- module Linear_format
- module Linearize
- module Linkage_name
  - module Map
  - module Set
  - module T
  - module Tbl
- module Linscan
- module Liveness
- module Mach
- module Mutable_variable
  - module Map
  - module Set
  - module T
  - module Tbl
- module Optcompile
- module Opterrors
- module Optmaindriver
- module Parameter
  - module List
  - module Map
  - module Set
  - module T
  - module Tbl
- module Pass_wrapper
- module Printclambda
- module Printclambda_primitives
- module Printcmm
- module Printlinear
- module Printmach
- module Proc
- module Projection
  - module Map
  - module Set
  - module T
  - module Tbl
- module Ref_to_variables
- module Reg
  - module Map
  - module Raw_name
  - module Set
- module Reg_availability_set
- module Reg_with_debug_info
  - module Debug_info
  - module Map_distinguishing_names_and_locations
  - module Set
  - module Set_distinguishing_names_and_locations
- module Reload
- module Reloadgen
  - reload_generic
- module Remove_free_vars_equal_to_args
- module Remove_unused_arguments
- module Remove_unused_closure_vars
- module Remove_unused_program_constructs
- module Schedgen
  - scheduler_generic
- module Scheduling
- module Selectgen
  - module Coeffect
  - module Effect
  - module Effect_and_coeffect
  - selector_generic
- module Selection
- module Semantics_of_primitives
- module Set_of_closures_id
  - module Map
  - module Set
  - module T
  - module Tbl
- module Set_of_closures_origin
  - module Map
  - module Set
  - module T
  - module Tbl
- module Share_constants
- module Simple_value_approx
- module Simplify_boxed_integer_ops
  - module Simplify_boxed_int32
  - module Simplify_boxed_int64
  - module Simplify_boxed_nativeint
- module Simplify_common
- module Simplify_primitives
- module Spill
- module Split
- module Static_exception
  - module Map
  - module Set
  - module T
  - module Tbl
- module Strmatch
  - module type I
  - module Make
    
    argument 1-_
- module Symbol
  - module Map
  - module Set
  - module T
  - module Tbl
- module Tag
  - module Map
  - module Set
  - module T
  - module Tbl
- module Traverse_for_exported_symbols
- module Un_anf
- module Unbox_closures
- module Unbox_free_vars_of_closures
- module Unbox_specialised_args
- module Var_within_closure
  - module Map
  - module Set
  - module T
  - module Tbl
- module Variable
  - module Map
  - module Pair
    
    module Map
    
    module Set
    
    module T
    
    module Tbl
  - module Set
  - module T
  - module Tbl
- module X86_dsl
  - module D
  - module I
- module X86_gas
- module X86_masm
- module X86_proc
library ocamltoplevel
- module Genprintval
  - module type EVALPATH
  - module Make
    
    argument 1-O
    
    argument 2-_
  - module type OBJ
  - module type S
- module Topdirs
- module Toploop
- module Topmain
- module Trace
library odoc_info
- module Odoc_analyse
- module Odoc_ast
  - module Analyser
    
    argument 1-_
  - module Typedtree_search
- module Odoc_class
- module Odoc_comments
  - module Basic_info_retriever
  - module type Texter
- module Odoc_comments_global
- module Odoc_config
- module Odoc_control
- module Odoc_cross
- module Odoc_dep
  - module Dep
- module Odoc_env
- module Odoc_exception
- module Odoc_extension
- module Odoc_global
- module Odoc_info
  - module Class
  - module Dep
  - module Exception
  - module Extension
  - module Global
  - module Module
  - module Name
  - module Parameter
  - module Scan
    
    scanner
  - module Search
  - module Type
  - module Value
- module Odoc_inherit
- module Odoc_lexer
- module Odoc_merge
- module Odoc_messages
- module Odoc_misc
- module Odoc_module
- module Odoc_name
  - module Map
- module Odoc_parameter
- module Odoc_parser
- module Odoc_print
- module Odoc_scan
  - scanner
- module Odoc_search
  - module P_name
  - module type Predicates
  - module Search
    
    argument 1-P
  - module Search_by_name
- module Odoc_see_lexer
- module Odoc_sig
  - module Analyser
    
    argument 1-_
  - module type Info_retriever
  - module Signature_search
- module Odoc_str
- module Odoc_text
  - module Texter
- module Odoc_text_lexer
- module Odoc_text_parser
- module Odoc_type
- module Odoc_types
- module Odoc_value
library stdlib
- module CamlinternalAtomic
- module CamlinternalFormat
- module CamlinternalFormatBasics
- module CamlinternalLazy
- module CamlinternalMod
- module CamlinternalOO
- module Stdlib
  - module Arg
  - module Array
  - module ArrayLabels
  - module Atomic
  - module Bigarray
    
    module Array0
    
    module Array1
    
    module Array2
    
    module Array3
    
    module Genarray
  - module Bool
  - module Buffer
  - module Bytes
  - module BytesLabels
  - module Callback
  - module Char
  - module Complex
  - module Digest
  - module Either
  - module Ephemeron
    
    module GenHashTable
    
    module MakeSeeded
    
    argument 1-H
    
    module K1
    
    module Make
    
    argument 1-H
    
    module MakeSeeded
    
    argument 1-H
    
    module K2
    
    module Make
    
    argument 1-H1
    
    argument 2-H2
    
    module MakeSeeded
    
    argument 1-H1
    
    argument 2-H2
    
    module Kn
    
    module Make
    
    argument 1-H
    
    module MakeSeeded
    
    argument 1-H
    
    module type S
    
    module type SeededS
  - module Filename
  - module Float
    
    module Array
    
    module ArrayLabels
  - module Format
  - module Fun
  - module Gc
    
    module Memprof
  - module Genlex
  - module Hashtbl
    
    module type HashedType
    
    module Make
    
    argument 1-H
    
    module MakeSeeded
    
    argument 1-H
    
    module type S
    
    module type SeededHashedType
    
    module type SeededS
  - module Int
  - module Int32
  - module Int64
  - module LargeFile
  - module Lazy
  - module Lexing
  - module List
  - module ListLabels
  - module Map
    
    module Make
    
    argument 1-Ord
    
    module type OrderedType
    
    module type S
  - module Marshal
  - module MoreLabels
    
    module Hashtbl
    
    module type HashedType
    
    module Make
    
    argument 1-H
    
    module MakeSeeded
    
    argument 1-H
    
    module type S
    
    module type SeededHashedType
    
    module type SeededS
    
    module Map
    
    module Make
    
    argument 1-Ord
    
    module type OrderedType
    
    module type S
    
    module Set
    
    module Make
    
    argument 1-Ord
    
    module type OrderedType
    
    module type S
  - module Nativeint
  - module Obj
    
    module Closure
    
    module Ephemeron
    
    module Extension_constructor
  - module Oo
  - module Option
  - module Parsing
  - module Pervasives
  - module Printexc
    
    module Slot
  - module Printf
  - module Queue
  - module Random
    
    module State
  - module Result
  - module Scanf
    
    module Scanning
  - module Seq
  - module Set
    
    module Make
    
    argument 1-Ord
    
    module type OrderedType
    
    module type S
  - module Stack
  - module StdLabels
  - module Stream
  - module String
  - module StringLabels
  - module Sys
    
    module Immediate64
    
    module type Immediate
    
    module Make
    
    argument 1-Immediate
    
    argument 2-Non_immediate
    
    module type Non_immediate
  - module Uchar
  - module Unit
  - module Weak
    
    module Make
    
    argument 1-H
    
    module type S
library str
- module Str
library threads
- module Condition
- module Event
- module Mutex
- module Semaphore
  - module Binary
  - module Counting
- module Thread
- module ThreadUnix
library unix
- module Unix
  - module LargeFile
- module UnixLabels
  - module LargeFile

type 'a t = unit -> 'a node

The type of delayed lists containing elements of type 'a. Note that the concrete list node 'a node is delayed under a closure, not a lazy block, which means it might be recomputed every time we access it.

and +'a node =

| Nil

| Cons of 'a * 'a t

A fully-evaluated list node, either empty or containing an element and a delayed tail.

val empty : 'a t

The empty sequence, containing no elements.

val return : 'a -> 'a t

The singleton sequence containing only the given element.

val cons : 'a -> 'a t -> 'a t

cons x xs is the sequence containing the element x followed by the sequence xs

since 4.11

val append : 'a t -> 'a t -> 'a t

append xs ys is the sequence xs followed by the sequence ys

since 4.11

val map : ( 'a -> 'b ) -> 'a t -> 'b t

map f seq returns a new sequence whose elements are the elements of seq, transformed by f. This transformation is lazy, it only applies when the result is traversed.

If seq = [1;2;3], then map f seq = [f 1; f 2; f 3].

val filter : ( 'a -> bool ) -> 'a t -> 'a t

Remove from the sequence the elements that do not satisfy the given predicate. This transformation is lazy, it only applies when the result is traversed.

val filter_map : ( 'a -> 'b option ) -> 'a t -> 'b t

Apply the function to every element; if f x = None then x is dropped; if f x = Some y then y is returned. This transformation is lazy, it only applies when the result is traversed.

val flat_map : ( 'a -> 'b t ) -> 'a t -> 'b t

Map each element to a subsequence, then return each element of this sub-sequence in turn. This transformation is lazy, it only applies when the result is traversed.

val fold_left : ( 'a -> 'b -> 'a ) -> 'a -> 'b t -> 'a

Traverse the sequence from left to right, combining each element with the accumulator using the given function. The traversal happens immediately and will not terminate on infinite sequences.

Also see List.fold_left

val iter : ( 'a -> unit ) -> 'a t -> unit

Iterate on the sequence, calling the (imperative) function on every element. The traversal happens immediately and will not terminate on infinite sequences.

val unfold : ( 'b -> ('a * 'b) option ) -> 'b -> 'a t

Build a sequence from a step function and an initial value. unfold f u returns empty if f u returns None, or fun () -> Cons (x, unfold f y) if f u returns Some (x, y).

For example, unfold (function [] -> None | h::t -> Some (h,t)) l is equivalent to List.to_seq l.

since 4.11