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  1. mapMOf :: LensLike (WrappedMonad m) s t a b -> (a -> m b) -> s -> m t

    dhall Dhall.Optics

    Identical to Control.Lens.mapMOf

  2. mapperIsLabelDeriver :: Deriver

    domain Domain

    Generates instances of IsLabel for sums and products, providing mappers over their components.

    Product Example

    Having the following schema: 
    NetworkAddress:
product:
protocol: TransportProtocol
host: Host
port: Word16
    The following instances will be generated: 
    instance
mapper ~ (TransportProtocol -> TransportProtocol) =>
IsLabel "protocol" (mapper -> NetworkAddress -> NetworkAddress)
where
fromLabel mapper (NetworkAddress a b c) =
NetworkAddress (mapper a) b c

instance
mapper ~ (Host -> Host) =>
IsLabel "host" (mapper -> NetworkAddress -> NetworkAddress)
where
fromLabel mapper (NetworkAddress a b c) =
NetworkAddress a (mapper b) c

instance
mapper ~ (Word16 -> Word16) =>
IsLabel "port" (mapper -> NetworkAddress -> NetworkAddress)
where
fromLabel mapper (NetworkAddress a b c) =
NetworkAddress a b (mapper c)
    In case you're wondering what this tilde (~) constraint business is about, refer to the Type Equality Constraint section.

    Sum Example

    Having the following schema: 
    Host:
sum:
ip: Ip
name: Text
    The following instances will be generated: 
    instance
mapper ~ (Ip -> Ip) =>
IsLabel "ip" (mapper -> Host -> Host)
where
fromLabel fn (IpHost a) = IpHost (fn a)
fromLabel _ a = a

instance
mapper ~ (Text -> Text) =>
IsLabel "name" (mapper -> Host -> Host)
where
fromLabel fn (NameHost a) = NameHost (fn a)
fromLabel _ a = a
    In case you're wondering what this tilde (~) constraint business is about, refer to the Type Equality Constraint section.

  3. mapException :: (Exception e1, Exception e2) => (e1 -> e2) -> a -> a

    effectful-core Effectful.Exception

    This function maps one exception into another as proposed in the paper "A semantics for imprecise exceptions".

  4. mapConsts :: (Expr -> Expr) -> Expr -> Expr

    express Data.Express

    O(n*m). Applies a function to all terminal constants in an expression. Given that: 

    > let one   = val (1 :: Int)
> let two   = val (2 :: Int)
> let xx -+- yy = value "+" ((+) :: Int->Int->Int) :$ xx :$ yy
> let intToZero e = if typ e == typ zero then zero else e
    Then: 
    > one -+- (two -+- xx)
1 + (2 + x) :: Int

    > mapConsts intToZero (one -+- (two -+- xx))
0 + (0 + x) :: Integer
    Given that the argument function is O(m), this function is O(n*m).

  5. mapSubexprs :: (Expr -> Maybe Expr) -> Expr -> Expr

    express Data.Express

    O(n*m). Substitute subexpressions of an expression using the given function. Outer expressions have more precedence than inner expressions. (cf. //) With: 

    > let xx = var "x" (undefined :: Int)
> let yy = var "y" (undefined :: Int)
> let zz = var "z" (undefined :: Int)
> let plus = value "+" ((+) :: Int->Int->Int)
> let times = value "*" ((*) :: Int->Int->Int)
> let xx -+- yy = plus :$ xx :$ yy
> let xx -*- yy = times :$ xx :$ yy

    > let pluswap (o :$ xx :$ yy) | o == plus = Just $ o :$ yy :$ xx
|     pluswap _                           = Nothing
    Then: 
    > mapSubexprs pluswap $ (xx -*- yy) -+- (yy -*- zz)
y * z + x * y :: Int

    > mapSubexprs pluswap $ (xx -+- yy) -*- (yy -+- zz)
(y + x) * (z + y) :: Int
    Substitutions do not stack, in other words a replaced expression or its subexpressions are not further replaced: 
    > mapSubexprs pluswap $ (xx -+- yy) -+- (yy -+- zz)
(y + z) + (x + y) :: Int
    Given that the argument function is O(m), this function is O(n*m).

  6. mapValues :: (Expr -> Expr) -> Expr -> Expr

    express Data.Express

    O(n*m). Applies a function to all terminal values in an expression. (cf. //-) Given that: 

    > let zero  = val (0 :: Int)
> let one   = val (1 :: Int)
> let two   = val (2 :: Int)
> let three = val (3 :: Int)
> let xx -+- yy = value "+" ((+) :: Int->Int->Int) :$ xx :$ yy
> let intToZero e = if typ e == typ zero then zero else e
    Then: 
    > one -+- (two -+- three)
1 + (2 + 3) :: Int

    > mapValues intToZero $ one -+- (two -+- three)
0 + (0 + 0) :: Integer
    Given that the argument function is O(m), this function is O(n*m).

  7. mapVars :: (Expr -> Expr) -> Expr -> Expr

    express Data.Express

    O(n*m). Applies a function to all variables in an expression. Given that: 

    > let primeify e = if isVar e
|                  then case e of (Value n d) -> Value (n ++ "'") d
|                  else e
> let xx = var "x" (undefined :: Int)
> let yy = var "y" (undefined :: Int)
> let xx -+- yy = value "+" ((+) :: Int->Int->Int) :$ xx :$ yy
    Then: 
    > xx -+- yy
x + y :: Int

    > primeify xx
x' :: Int

    > mapVars primeify $ xx -+- yy
x' + y' :: Int

    > mapVars (primeify . primeify) $ xx -+- yy
x'' + y'' :: Int
    Given that the argument function is O(m), this function is O(n*m).

  8. map' :: Expr -> Expr -> Expr

    express Data.Express.Fixtures

    map lifted over Exprs. 

    > map' absE (unit one)
map abs [1] :: [Int]

  9. mapE :: Expr

    express Data.Express.Fixtures

    map over the Int element type encoded as an Expr 

    > mapE
map :: (Int -> Int) -> [Int] -> [Int]

  10. mapConsts :: (Expr -> Expr) -> Expr -> Expr

    express Data.Express.Map

    O(n*m). Applies a function to all terminal constants in an expression. Given that: 

    > let one   = val (1 :: Int)
> let two   = val (2 :: Int)
> let xx -+- yy = value "+" ((+) :: Int->Int->Int) :$ xx :$ yy
> let intToZero e = if typ e == typ zero then zero else e
    Then: 
    > one -+- (two -+- xx)
1 + (2 + x) :: Int

    > mapConsts intToZero (one -+- (two -+- xx))
0 + (0 + x) :: Integer
    Given that the argument function is O(m), this function is O(n*m).

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