global: Handling global entities in programs

This package contains a library Data.Global to handle global entities in Curry programs. A global entity has a name declared in the program. Its value can be accessed and modified by IO actions.

Global entities can be declared as persistent so that their values are stored across different program executions or temporary so that they will be stored only in memory.

Currently, it is still experimental so that its interface might be slightly changed in the future.

Usage

A temporary global entity gt is a top-level constant of type GlobalT t. If v is an initial value v of type t, where the type t does not contain type variables or type class contraints, the temporary global entity should be declared in a module Mod by:

gt :: GlobalT t
gt = globalT "Mod.gt" v

The first argument is the qualified name of this program entity and used as a unique name for this global value.

Similarly, a persistent global entity gp with an initial value v of type t could be declared by:

gt :: GlobalP t
gt = globalPersistent f v

where the type t must not contain type variables and support Read and Show instances. f is the file name where the global value is persistently stored (the file is created and initialized with v if it does not exist).