by Dave Herman (dherman at ccs dot neu dot edu)
This library provides several utilities for parameters.
Everything in this library is exported by a single module:
(require (planet dherman/parameter:1))
A pseudo-parameter is like a PLT Scheme parameter, but comprises both an accessor and a mutator function. This can be used, for example, to create compound parameters that simultaneously update multiple parameters.
( getter setter) → ( a)
getter : (-> a)
setter : (a -> any)
Constructs a new pseudo-parameter with getter and setter functions.
( x) → boolean?
x : any
Determines whether a given value is a pseudo-parameter.
( c) → contract?
c : contract?
A contract constructor for pseudo-parameters with an underlying value of contract c.
A parameter set is a collection of PLT Scheme parameters that can be read or written to all at once with a prefab structure. Because the structure is prefab, a parameter set can also easily be marshalled and demarshalled (assuming its values are all writeable, of course).
Defines a parameter set. The struct-id is defined as a prefab structure type with one field for each parameter in the set, in declaration order. The pseudo-id is defined as a pseudo-parameter that reads or writes the values of all the parameters in the set simultaneously. Each param-id is defined as a parameter with default value computed by default-expr and optional guard computed by maybe-guard.