init commit again

IBAF-cbs/Funcons-beta/Computations/Abnormal/Breaking/Breaking.cbs

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+### Breaking
+
+[
+  Datatype breaking
+  Funcon   broken
+  Funcon   finalise-breaking
+  Funcon   break
+  Funcon   handle-break
+]
+
+
+Meta-variables
+  T <: values
+
+
+Datatype
+  breaking ::= broken
+/*
+  `broken` is a reason for abrupt termination.
+*/
+
+
+Funcon
+  finalise-breaking(X:=>T) : =>T|null-type
+   ~> finalise-abrupting(X)
+/*
+  `finalise-breaking(X)` handles abrupt termination of `X` due to executing
+  `break`.
+*/
+
+
+Funcon
+  break : =>empty-type
+   ~> abrupt(broken)
+/*
+  `break` abruptly terminates all enclosing computations until it is handled.
+*/
+
+
+Funcon
+  handle-break(_:=>null-type) : =>null-type
+/*
+  `handle-break(X)` terminates normally when `X` terminates abruptly for the
+  reason `broken`.
+*/
+Rule
+                X --abrupted( )-> X'
+  ------------------------------------------------
+  handle-break(X) --abrupted( )-> handle-break(X')
+Rule
+                X --abrupted(broken)-> _
+  ---------------------------------------
+  handle-break(X) --abrupted( )-> null-value
+Rule
+                X --abrupted(V:~breaking)-> X'
+  ------------------------------------------------
+  handle-break(X) --abrupted(V)-> handle-break(X')
+Rule
+  handle-break(null-value) ~> null-value