std.functional

Functions that manipulate other functions.

This module provides functions for compile time function composition. These functions are helpful when constructing predicates for the algorithms in std.algorithm or std.range.


Function Name	Description
adjoin	Joins a couple of functions into one that executes the original functions independently and returns a tuple with all the results.
compose, pipe	Join a couple of functions into one that executes the original functions one after the other, using one function's result for the next function's argument.
forward	Forwards function arguments while saving ref-ness.
lessThan, greaterThan, equalTo	Ready-made predicate functions to compare two values.
memoize	Creates a function that caches its result for fast re-evaluation.
not	Creates a function that negates another.
partial	Creates a function that binds the first argument of a given function to a given value.
curry	Converts a multi-argument function into a series of single-argument functions. f(x, y) == curry(f)(x)(y)
reverseArgs	Predicate that reverses the order of its arguments.
toDelegate	Converts a callable to a delegate.
unaryFun, binaryFun	Create a unary or binary function from a string. Most often used when defining algorithms on ranges.

Members

Aliases

equalTo alias equalTo = safeOp!"==": Predicate that returns a == b. Correctly compares signed and unsigned integers, ie. !(-1 == ~0U).
greaterThan alias greaterThan = safeOp!">": Predicate that returns a > b. Correctly compares signed and unsigned integers, ie. 2U > -1.
lessThan alias lessThan = safeOp!"<": Predicate that returns a < b. Correctly compares signed and unsigned integers, ie. -1 < 2U.
pipe alias pipe(fun...) = compose!(Reverse!(fun)): Pipes functions in sequence. Offers the same functionality as compose, but with functions specified in reverse order. This may lead to more readable code in some situation because the order of execution is the same as lexical order.

Functions

curry auto curry(T t): Takes a function of (potentially) many arguments, and returns a function taking one argument and returns a callable taking the rest. f(x, y) == curry(f)(x)(y)
toDelegate auto toDelegate(F fp): Convert a callable to a delegate with the same parameter list and return type, avoiding heap allocations and use of auxiliary storage.

Templates

adjoin template adjoin(F...): Takes multiple functions and adjoins them together.
binaryFun template binaryFun(alias fun, string parm1Name = "a", string parm2Name = "b"): Transforms a string representing an expression into a binary function. The string must either use symbol names a and b as the parameters or provide the symbols via the parm1Name and parm2Name arguments.
compose template compose(fun...): Composes passed-in functions fun[0], fun[1], ....
curry template curry(alias F): Takes a function of (potentially) many arguments, and returns a function taking one argument and returns a callable taking the rest. f(x, y) == curry(f)(x)(y)
forward template forward(args...): Forwards function arguments while keeping out, ref, and lazy on the parameters.
memoize template memoize(alias fun)
template memoize(alias fun, uint maxSize): * Memoizes a function so as * to avoid repeated computation. The memoization structure is a hash table keyed by a * tuple of the function's arguments. There is a speed gain if the * function is repeatedly called with the same arguments and is more * expensive than a hash table lookup. For more information on memoization, refer to this book chapter.
not template not(alias pred): Negates predicate pred.
partial template partial(alias fun, alias arg): Partially applies fun by tying its first argument to arg.
reverseArgs template reverseArgs(alias pred): N-ary predicate that reverses the order of arguments, e.g., given pred(a, b, c), returns pred(c, b, a).
unaryFun template unaryFun(alias fun, string parmName = "a"): Transforms a string representing an expression into a unary function. The string must either use symbol name a as the parameter or provide the symbol via the parmName argument.

std.functional

Members

Aliases

Functions

Templates

Meta

Source

License

Copyright

Authors