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The basics
Installation
Thinking in pipelines
Designing with states
Composition utilities
Errors & absence
Maybe — Modeling Absence
Result — Modeling Failures
Validation — Accumulating Errors
These — Inclusive OR
Async
Task — Lazy Asynchronous Work
Deferred — Infallible Async Values
Op — Managing Async Operations
RemoteData — Loading States
Resource — Safe Lifecycle Management
State & context
Reader — Shared Contexts
State — Stateful Computations
Logged — Accumulated Logs
Nested data
Lens — Nested Updates
Optional — Nullable Paths
Tuple — Typed Pairs
Type safety
Brand — Distinguishing Values
Duration — Type-Safe Time
Refinement — Type Predicates
Predicate — Composable Logic
Comparing & combining
Equality — Composable Equality Checks
Ordering — Composable Comparators
Combinable — Combining Values
Lazy — Memoized Computations
Collection utilities
Arr — Array Utilities
Str — String Utilities
Num — Number Utilities
Rec — Record Utilities
Dict — Dictionary Utilities
Uniq — Unique Collections
Appendix
Why this exists
Design and influences
Performance and benchmarks
API Reference
Composition
Interfaces
flow
pipe
Functions
and
compose
constant
constFalse
constNull
constTrue
constUndefined
constVoid
converge
curry
curry3
curry4
defaultTo
flip
flow
identity
juxt
memoize
memoizeWeak
not
on
once
or
pipe
tap
uncurry
uncurry3
uncurry4
Core
Namespaces
Combinable
functions
array
fold
maybe
variables
all
any
product
string
sum
Deferred
functions
fromPromise
toPromise
Equality
functions
and
array
by
variables
boolean
date
number
string
Lazy
functions
chain
evaluate
from
map
tap
Lens
functions
andThen
andThenOptional
get
make
modify
prop
set
toOptional
Logged
functions
ap
bind
bindTo
chain
make
map
run
tap
tell
Maybe
functions
ap
bind
bindTo
chain
filter
fold
fromNullable
fromPredicate
fromResult
getOrElse
isNone
isSome
map
match
none
recover
some
struct
tap
toNullable
toResult
toUndefined
Op
functions
all
chain
create
err
fold
getOrElse
interpret
isErr
isIdle
isNil
isOk
isPending
isQueued
isRetrying
lift
map
mapError
match
nil
ok
race
recover
tap
toMaybe
toResult
wire
type-aliases
AbortedNil
BufferedState
ConcurrentDropState
ConcurrentQueueState
DebouncedState
DroppedNil
Err
EvictedNil
ExclusiveState
Idle
KeyedExclusivePerKey
KeyedManager
KeyedRestartablePerKey
Manager
Nil
NilReason
Ok
OnceState
Outcome
Pending
Queued
QueueDropAndReplaceState
QueueDropState
QueueReplaceState
QueueState
ReplacedNil
RestartableState
RetryableBufferedState
RetryableConcurrentDropState
RetryableConcurrentQueueState
RetryableDebouncedState
RetryableExclusiveState
RetryableOnceState
RetryableQueueDropAndReplaceState
RetryableQueueDropState
RetryableQueueReplaceState
RetryableQueueState
RetryableRestartableState
RetryableThrottledState
RetryableThrottledTrailingState
Retrying
RetryOptions
State
ThrottledState
ThrottledTrailingState
TimeoutOptions
Optional
functions
index
andThen
andThenLens
fold
get
getOrElse
make
match
modify
prop
set
Ordering
functions
by
reverse
thenBy
variables
date
number
string
Predicate
functions
all
and
any
fromRefinement
not
or
using
Reader
functions
ap
ask
asks
bind
bindTo
chain
local
map
resolve
run
tap
Refinement
functions
and
compose
make
or
toFilter
toResult
RemoteData
functions
ap
chain
failure
filter
fold
fromMaybe
fromResult
getOrElse
isFailure
isLoading
isNotAsked
isSuccess
loading
map
mapError
match
notAsked
recover
success
tap
tapError
toMaybe
toResult
Resource
functions
combine
fromTask
make
use
Result
functions
ap
bind
bindTo
chain
err
fold
fromMaybe
fromNullable
fromPredicate
fromThrowable
getOrElse
isErr
isOk
map
mapError
match
ok
recover
recoverUnless
struct
tap
tapError
toMaybe
tryCatch
State
functions
ap
bind
bindTo
chain
evaluate
execute
get
gets
map
modify
put
resolve
run
tap
Task
functions
abortable
all
ap
bind
bindTo
chain
delay
from
fromSync
map
race
repeat
repeatUntil
resolve
run
sequence
sequential
tap
timeout
TaskMaybe
functions
ap
bind
bindTo
chain
filter
fold
fromMaybe
fromNullable
fromResult
fromTask
getOrElse
map
match
none
some
tap
toTaskResult
tryCatch
TaskResult
functions
ap
bind
bindTo
chain
err
fold
fromMaybe
fromNullable
fromResult
fromThrowable
getOrElse
map
mapError
match
ok
recover
run
struct
tap
tapError
tryCatch
TaskValidation
functions
ap
failed
failedAll
fold
fromMaybe
fromNullable
fromResult
fromValidation
getOrElse
map
match
passed
product
productAll
recover
tap
tryCatch
These
functions
both
chainFirst
chainSecond
first
fold
getFirstOrElse
getSecondOrElse
hasFirst
hasSecond
isBoth
isFirst
isSecond
mapBoth
mapFirst
mapSecond
match
second
swap
tap
Tuple
functions
first
fold
make
mapBoth
mapFirst
mapSecond
second
swap
tap
toArray
Validation
functions
ap
failed
failedAll
fold
fromMaybe
fromNullable
fromPredicate
fromResult
getOrElse
isFailed
isPassed
map
mapError
match
passed
product
productAll
recover
recoverUnless
struct
tap
tapError
toMaybe
toResult
Type Aliases
Combinable
Deferred
Equality
Err
Failed
Failure
Lazy
Lens
Loading
Logged
Maybe
None
NotAsked
Ok
Op
Optional
Ordering
Passed
Predicate
Reader
Refinement
RemoteData
Resource
Result
Some
State
Success
Task
TaskMaybe
TaskResult
TaskValidation
These
TheseBoth
TheseFirst
TheseSecond
Tuple
Validation
Data
Namespaces
Arr
functions
chunksOf
compact
drop
dropWhile
every
filter
filterMap
findFirst
findIndex
findLast
flatMap
flatten
groupBy
head
init
insertAt
intersperse
isNonEmpty
last
map
mapWithIndex
partition
partitionMap
reduce
removeAt
reverse
scan
separate
sequence
sequenceResult
sequenceTask
sequenceTaskResult
size
some
sortBy
sortWith
splitAt
tail
take
takeWhile
traverse
traverseResult
traverseTask
traverseTaskResult
uniq
uniqBy
uniqWith
zip
zipWith
Dict
functions
compact
difference
empty
entries
filter
filterMap
filterWithKey
fromEntries
fromRecord
groupBy
has
insert
intersection
isEmpty
keys
lookup
map
mapWithKey
reduce
reduceWithKey
remove
singleton
size
toRecord
union
upsert
values
Num
functions
abs
add
between
ceil
clamp
divide
floor
max
mean
min
multiply
negate
parse
range
remainder
round
subtract
sum
Rec
functions
compact
entries
filter
filterMap
filterWithKey
fromEntries
groupBy
isEmpty
keys
lookup
map
mapKeys
mapWithKey
merge
omit
pick
size
values
Str
functions
capitalize
endsWith
includes
isBlank
isEmpty
length
lines
padEnd
padStart
parseJson
replace
replaceAll
slice
split
startsWith
toLowerCase
toUpperCase
trim
words
variables
parse
Uniq
functions
difference
empty
filter
fromArray
has
insert
intersection
isEmpty
isSubsetOf
map
reduce
remove
singleton
size
toArray
union
Types
Namespaces
Brand
functions
unwrap
wrap
Duration
functions
add
days
hours
milliseconds
minutes
seconds
subtract
toDays
toHours
toMilliseconds
toMinutes
toSeconds
Type Aliases
Brand
Duration
NonEmptyList
Functions
isNonEmptyList
GitHub
npm
none
none
():
None
Defined in:
Core/Maybe.ts:40
Creates a None (empty Maybe).
Returns
Section titled “Returns”
None