Capabilities
compose-capability
capability -> bool → bool
Specifies and requests grant of CAPABILITY which is an application of a 'defcap' production, only valid within a (distinct) 'defcap' body, as a way to compose CAPABILITY with the outer capability such that the scope of the containing 'with-capability' call will "import" this capability. Thus, a call to '(with-capability (OUTER-CAP) OUTER-BODY)', where the OUTER-CAP defcap calls '(compose-capability (INNER-CAP))', will result in INNER-CAP being granted in the scope of OUTER-BODY.
(compose-capability (TRANSFER src dest))(compose-capability (TRANSFER src dest))emit-event
capability -> bool → bool
Emit CAPABILITY as event without evaluating body of capability. Fails if CAPABILITY is not @managed or @event.
(emit-event (TRANSFER "Bob" "Alice" 12.0))(emit-event (TRANSFER "Bob" "Alice" 12.0))enforce-guard
guard guard → bool
keysetname string → bool
Execute GUARD, or defined keyset KEYSETNAME, to enforce desired predicate logic.
(enforce-guard 'admin-keyset)
(enforce-guard row-guard)(enforce-guard 'admin-keyset)
(enforce-guard row-guard)install-capability
capability -> bool → string
Specifies, and provisions install of, a managed CAPABILITY, defined in a 'defcap' in which a '@managed' tag designates a single parameter to be managed by a specified function. After install, CAPABILITY must still be brought into scope using 'with-capability', at which time the 'manager function' is invoked to validate the request. The manager function is of type 'managed:<p> requested:<p> -> <p>', where '<p>' indicates the type of the managed parameter, such that for '(defcap FOO (bar:string baz:integer) @managed baz FOO-mgr ...)', the manager function would be '(defun FOO-mgr:integer (managed:integer requested:integer) ...)'. Any capability matching the 'static' (non-managed) parameters will cause this function to be invoked with the current managed value and that of the requested capability. The function should perform whatever logic, presumably linear, to validate the request, and return the new managed value representing the 'balance' of the request. NOTE that signatures scoped to a managed capability cause the capability to be automatically provisioned for install similarly to one installed with this function.
(install-capability (PAY "alice" "bob" 10.0))(install-capability (PAY "alice" "bob" 10.0))require-capability
capability -> bool → bool
Specifies and tests for existing grant of CAPABILITY, failing if not found in environment.
(require-capability (TRANSFER src dest))(require-capability (TRANSFER src dest))with-capability
capability -> bool body [*] → <a>
Specifies and requests grant of acquired CAPABILITY which is an application of a 'defcap' production. Given the unique token specified by this application, ensure that the token is granted in the environment during execution of BODY. 'with-capability' can only be called in the same module that declares the corresponding 'defcap', otherwise module-admin rights are required. If token is not present, the CAPABILITY is evaluated, with successful completion resulting in the installation/granting of the token, which will then be revoked upon completion of BODY. Nested 'with-capability' calls for the same token will detect the presence of the token, and will not re-apply CAPABILITY, but simply execute BODY. 'with-capability' cannot be called from within an evaluating defcap. Acquire of a managed capability results in emission of the equivalent event.
(with-capability (UPDATE-USERS id) (update users id { salary: new-salary }))(with-capability (UPDATE-USERS id) (update users id { salary: new-salary }))