IBAFLang/IBAF-cbs/Funcons-beta/Values/Abstraction/Functions/index.md

layout, title, parent, ancestor

layout	title	parent	ancestor
default	Functions	Abstraction	Funcons-beta

Funcons-beta : Functions.cbs

Functions

[
  Datatype functions
  Funcon   function
  Funcon   apply
  Funcon   supply
  Funcon   compose
  Funcon   uncurry
  Funcon   curry
  Funcon   partial-apply
]

Meta-variables
  T, T′, T1, T2 <: values

Datatype
  functions(T,T′) ::= function(A:abstractions(T=>T′))

functions(T, T′) consists of abstractions whose bodies may depend on a given value of type T, and whose executions normally compute values of type T′. function(abstraction(X)) evaluates to a function with dynamic bindings, function(closure(X)) computes a function with static bindings.

Funcon
  apply(_:functions(T, T′), _:T) : =>T′

apply(F, V) applies the function F to the argument value V. This corresponds to call by value; using thunks as argument values corresponds to call by name. Moreover, using tuples as argument values corresponds to application to multiple arguments.

Rule
  apply(function(abstraction(X)), V:T) ~> give(V, X)

Funcon
  supply(_:functions(T, T′), _:T) : =>thunks(T′)

supply(F, V) determines the argument value of a function application, but returns a thunk that defers executing the body of the function.

Rule
  supply(function(abstraction(X)), V:T) ~> thunk(abstraction(give(V, X)))

Funcon
  compose(_:functions(T2, T′), _:functions(T1, T2)) : =>functions(T1, T′)

compose(F2, F1) returns the function that applies F1 to its argument, then applies F2 to the result of F1.

Rule
  compose(function(abstraction(Y)), function(abstraction(X)))
    ~> function(abstraction(give(X, Y)))

Funcon
  uncurry(F:functions(T1, functions(T2, T′))) : 
    =>functions(tuples(T1, T2), T′)
   ~> function(abstraction(
         apply(
           apply(F, checked index(1, tuple-elements given)),
           checked index(2, tuple-elements given))))

uncurry(F) takes a curried function F and returns a function that takes a pair of arguments..

Funcon
  curry(F:functions(tuples(T1, T2), T′)) : =>functions(T1, functions(T2, T′))
    ~> function(abstraction(partial-apply(F, given)))

curry(F) takes a function F that takes a pair of arguments, and returns the corresponding 'curried' function.

Funcon
  partial-apply(F:functions(tuples(T1, T2), T′), V:T1) : =>functions(T2, T′)
    ~> function(abstraction(apply(F,tuple(V,given))))

partial-apply(F, V) takes a function F that takes a pair of arguments, and determines the first argument, returning a function of the second argument.

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