base
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library base
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module Base
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module Applicative
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module type Applicative_infix
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module type Applicative_infix2
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module type Applicative_infix3
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module type Basic
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module type Basic2
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module type Basic2_using_map2
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module type Basic3
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module type Basic3_using_map2
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module type Basic_using_map2
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module Compose
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argument 1-F
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module Applicative_infix
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argument 2-G
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module Applicative_infix
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module Applicative_infix
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module type Let_syntax
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module Let_syntax
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module Let_syntax
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module Open_on_rhs_intf
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module type Let_syntax2
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module Let_syntax
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module Let_syntax
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module Open_on_rhs_intf
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module type Let_syntax3
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module Let_syntax
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module Let_syntax
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module Open_on_rhs_intf
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module Make
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argument 1-X
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module Applicative_infix
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module Make2
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argument 1-X
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module Applicative_infix
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module Make2_using_map2
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argument 1-X
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module Applicative_infix
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module Make3
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argument 1-X
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module Applicative_infix
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module Make3_using_map2
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argument 1-X
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module Applicative_infix
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module Make_let_syntax
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argument 1-X
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argument 2-Intf
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module Let_syntax
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module Let_syntax
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-
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module Make_let_syntax2
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argument 1-X
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argument 2-Intf
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module Let_syntax
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module Let_syntax
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-
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module Make_let_syntax3
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argument 1-X
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argument 2-Intf
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module Let_syntax
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module Let_syntax
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-
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module Make_using_map2
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argument 1-X
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module Applicative_infix
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module Of_monad
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argument 1-M
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Applicative_infix
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module Of_monad2
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argument 1-M
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Applicative_infix
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module Pair
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argument 1-F
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module Applicative_infix
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argument 2-G
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module Applicative_infix
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module Applicative_infix
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module type S
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module Applicative_infix
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module type S2
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module Applicative_infix
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module S2_to_S
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argument 1-X
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module Applicative_infix
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module Applicative_infix
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module S2_to_S3
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argument 1-X
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module Applicative_infix
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module Applicative_infix
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module type S3
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module Applicative_infix
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module S3_to_S2
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argument 1-X
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module Applicative_infix
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module Applicative_infix
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module S_to_S2
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argument 1-X
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module Applicative_infix
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module Applicative_infix
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-
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module Array
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module Avltree
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module Binary_search
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module Binary_searchable
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module type Indexable
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module type Indexable1
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module type S
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module type S1
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module Blit
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module Make
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argument 1-Sequence
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module Make1
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argument 1-Sequence
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module Make1_generic
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argument 1-Sequence
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module Make_distinct
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module Make_to_string
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argument 1-T
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argument 2-To_bytes
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module type S
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module type S1
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module type S1_distinct
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module type S_distinct
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module type S_to_string
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module type Sequence
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module type Sequence1
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module Bool
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module Non_short_circuiting
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module Bytes
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module From_string
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module To_string
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module Comparable
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module Make_using_comparator
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argument 1-T
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module Polymorphic_compare
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argument 1-T
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module type S
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module Validate_with_zero
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argument 1-T
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module Comparisons
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module Container
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module Continue_or_stop
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module type Generic
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module type Generic_phantom
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module type S0
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module type S0_phantom
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module type S1
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module type S1_phantom
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module type S1_phantom_invariant
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module type Summable
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module Continue_or_stop
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module Either
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module First
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module Applicative_infix
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module type Focused
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module Applicative_infix
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Second
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module Applicative_infix
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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-
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module Error
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module Internal_repr
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module Exn
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module Export
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module Field
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module Fn
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module Formatter
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module Hashtbl
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module type Accessors
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module type For_deriving
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module type M_of_sexp
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module Merge_into_action
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module type Multi
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module Poly
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module type S_poly
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module type S_without_submodules
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module type Sexp_of_m
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module Identifiable
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module Make_using_comparator
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argument 1-M
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module type S
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module Indexed_container
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module type S1
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module Info
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module Internal_repr
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module type S
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module Internal_repr
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-
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module Int
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module Hex
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module type Int_without_module_types
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module O
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module type Operators
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module type Operators_unbounded
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module type Round
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module type S_unbounded
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module Int63
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module Hex
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module O
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module Overflow_exn
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module Lazy
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module T_unforcing
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module Linked_queue
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module List
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module Assoc
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module Infix
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Or_unequal_lengths
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module Map
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module type Accessors1
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module type Accessors2
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module type Accessors3
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module type Accessors3_with_comparator
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module type Accessors_generic
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module type Compare_m
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module Continue_or_stop
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module type Creators1
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module type Creators2
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module type Creators3_with_comparator
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module type Creators_and_accessors1
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module type Creators_and_accessors2
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module type Creators_and_accessors3_with_comparator
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module type Creators_and_accessors_generic
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module type Creators_generic
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module type Equal_m
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module Finished_or_unfinished
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module type For_deriving
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module type M_of_sexp
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module Or_duplicate
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module Poly
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module type S_poly
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module type Sexp_of_m
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module Symmetric_diff_element
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module Using_comparator
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module Empty_without_value_restriction
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argument 1-K
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module Tree
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module With_comparator
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module With_first_class_module
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module Without_comparator
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module Maybe_bound
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module Monad
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module type Basic
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module type Basic2
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module type Basic3
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module type Basic_indexed
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module Ident
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module type Infix
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module type Infix2
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module type Infix3
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module type Infix_indexed
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module Make
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argument 1-X
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Make2
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argument 1-X
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Make3
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argument 1-X
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Make_indexed
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argument 1-X
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module type S
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module type S2
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module type S3
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module type S_indexed
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module type S_without_syntax
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module Monad_infix
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module type Syntax
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
-
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module type Syntax2
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
-
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module type Syntax3
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
-
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module type Syntax_indexed
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
-
-
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module Nothing
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module Option
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Option_array
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module Or_error
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module Applicative_infix
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Ordered_collection_common
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module Private
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module Poly
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module Popcount
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module Pretty_printer
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module Register_pp
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argument 1-M
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module type S
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module Printf
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module Result
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module Export
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Sequence
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module Expert
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module Generator
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Infix
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module Let_syntax
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module Let_syntax
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module Open_on_rhs
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-
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module Monad_infix
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module Step
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module Set
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module type Accessors0
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module Named
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-
module type Accessors1
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module Named
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-
module type Accessors2
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module Named
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module type Accessors2_with_comparator
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module Named
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module type Accessors_generic
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module Named
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module type Compare_m
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module type Creators0
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module type Creators1
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module type Creators2
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module type Creators2_with_comparator
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module type Creators_and_accessors0
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module Named
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module type Creators_and_accessors1
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module Named
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module type Creators_and_accessors2
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module Named
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module type Creators_and_accessors2_with_comparator
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module Named
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module type Creators_generic
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module type Elt_plain
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module type Equal_m
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module type For_deriving
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module type M_of_sexp
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module Merge_to_sequence_element
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module Named
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module type Sexp_of_m
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module Using_comparator
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module Empty_without_value_restriction
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argument 1-Elt
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module Named
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module With_comparator
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module With_first_class_module
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module Without_comparator
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module Sexp
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module Private
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module Raw_grammar
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-
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module Sexpable
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module Of_sexpable
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argument 1-Sexpable
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argument 2-M
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module Of_sexpable1
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argument 1-Sexpable
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argument 2-M
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module Of_sexpable2
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argument 1-Sexpable
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argument 2-M
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module Of_sexpable3
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argument 1-Sexpable
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argument 2-M
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module Of_stringable
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argument 1-M
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module type S
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module type S1
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module type S2
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module type S3
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module Sign
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module Sign_or_nan
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module Source_code_position
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module Staged
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module String
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module Caseless
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module Escaping
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module Search_pattern
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module Stringable
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module type S
-
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module Sys
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module type T1
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module type T2
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module type T3
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module Type_equal
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module type Injective
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module type Injective2
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module Uchar
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module Uniform_array
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module Unit
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module Variant
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module With_return
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module Word_size
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-
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library base.base_internalhash_types
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module Base_internalhash_types
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library base.caml
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module Caml
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library base.md5
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module Md5_lib
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library base.shadow_stdlib
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module Shadow_stdlib
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module type Full = sig ... end
module type S = sig ... end
module F
(Hash : S) :
Full
with type hash_value = Hash.hash_value
and type state = Hash.state
and type seed = Hash.seed
The code of ppx_hash
is agnostic to the choice of hash algorithm that is used. However, it is not currently possible to mix various choices of hash algorithms in a given code base.
We experimented with:
- (a) custom hash algorithms implemented in OCaml and
- (b) in C;
- (c) OCaml's internal hash function (which is a custom version of Murmur3, implemented in C);
- (d) siphash, a modern hash function implemented in C.
Our findings were as follows:
- Implementing our own custom hash algorithms in OCaml and C yielded very little performance improvement over the (c) proposal, without providing the benefit of being a peer-reviewed, widely used hash function.
- Siphash (a modern hash function with an internal state of 32 bytes) has a worse performance profile than (a,b,c) above (hashing takes more time). Since its internal state is bigger than an OCaml immediate value, one must either manage allocation of such state explicitly, or paying the cost of allocation each time a hash is computed. While being a supposedly good hash function (with good hash quality), this quality was not translated in measurable improvements in our macro benchmarks. (Also, based on the data available at the time of writing, it's unclear that other hash algorithms in this class would be more than marginally faster.)
- By contrast, using the internal combinators of OCaml hash function means that we do not allocate (the internal state of this hash function is 32 bit) and have the same quality and performance as Hashtbl.hash.
Hence, we are here making the choice of using this Internalhash (that is, Murmur3, the OCaml hash algorithm as of 4.03) as our hash algorithm. It means that the state of the hash function does not need to be preallocated, and makes for simpler use in hash tables and other structures.
include Full
with type state = Base_internalhash_types.state
and type seed = Base_internalhash_types.seed
and type hash_value = Base_internalhash_types.hash_value
type state = Base_internalhash_types.state
state
is the internal hash-state used by the hash function.
fold_<T> state v
incorporates a value v
of type <T> into the hash-state, returning a modified hash-state. Implementations of the fold_<T>
functions may mutate the state
argument in place, and return a reference to it. Implementations of the fold_<T> functions should not allocate.
type seed = Base_internalhash_types.seed
seed
is the type used to seed the initial hash-state.
val alloc : unit -> state
alloc ()
returns a fresh uninitialized hash-state. May allocate.
reset ?seed state
initializes/resets a hash-state with the given seed
, or else a default-seed. Argument state
may be mutated. Should not allocate.
type hash_value = Base_internalhash_types.hash_value
hash_value
The type of hash values, returned by get_hash_value
.
val get_hash_value : state -> hash_value
get_hash_value
extracts a hash-value from the hash-state.
module For_tests : sig ... end
create ?seed ()
is a convenience. Equivalent to reset ?seed (alloc ())
.
val of_fold : ( state -> 'a -> state ) -> 'a -> hash_value
of_fold fold
constructs a standard hash function from an existing fold function.
module Builtin : sig ... end
val run : ?seed:seed -> 'a folder -> 'a -> hash_value
run ?seed folder x
runs folder
on x
in a newly allocated hash-state, initialized using optional seed
or a default-seed.
The following identity exists: run [%hash_fold: T]
== [%hash: T]
run
can be used if we wish to run a hash-folder with a non-default seed.