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+Context
+=======
+
+Context (also known as environment in some of Lisp implementations)
+is association between symbols and their data values that apply to
+specific evaluation scope. This implementation provides single
+lexical context for evaluation of all names regarding of associated data
+type (also known as Lisp-1 namespaces).
+
+Basic method of introducing new scope is function definition and application.
+During function definition, new function is associated with scope in which
+function itself is defined. Exact copy of current context as is in moment
+of definition is used as functions parent scope. During function application
+new context is created which inherit all associations that were available
+in parent scope.
+
+Initial context, which is used as starting context, is initialized with
+associations to builtin functions and syntaxes.
+
+Each context contains arbitrary number of mutable entries. Single entry
+defines association where any kind of data is referenced by symbol.
+Together with functions that add new entries (`lsp_ctx_add`) or obtain
+data associated with provided symbol (`lsp_ctx_get`), context enables
+modification of data referenced by provided symbol (`lsp_ctx_set`).
+During entry modification, previous data instance itself is not changed, only
+entry reference is modified to point to newly provided data instance.
+If child context modifies existing entry in parent context, this modifications
+will also be visible in parent context.
+
+Because of support for
+`tail call optimization <https://en.wikipedia.org/wiki/Tail_call>`_,
+implementation of context hierarchy relies on `lsp_ctx_copy` operation instead
+of referencing parent context from child context. This method induces
+additional overhead in context operation. Never the less, additional memory
+allocation overhead is mostly neutralized by usage of immutable linked list
+as basis for entry storage.
+
+
+Source code
+-----------
+
+ctx.h
+'''''
+
+.. literalinclude:: ../src_c/ctx.h
+    :language: c
+
+
+ctx.c
+'''''
+
+.. literalinclude:: ../src_c/ctx.c
+    :language: c