Make the introduction more precise

README.md

@@ -5,12 +5,12 @@ Haskell 2010 extended with higher-rank polymorphism is approximately
 System F*ω* and thus roughly corresponds to intuitionistic higher-order
 propositional logic via a Curry–Howard isomorphism. GHC’s static
 pointers extension, while having been conceived specifically for
-distributed programming, further extends Haskell such that it becomes a
-kind of generic modal programming language. This allows programmers to
-write libraries that turn Haskell into the Curry–Howard correspondents
-of various modal logics and to combine these libraries to arrive at
-programming languages that integrate multiple modal features. The
-`modal-programming` package provides support for writing such libraries.
+distributed programming, makes it possible to turn Haskell into the
+Curry–Howard correspondents of typical modal logics. Since the static
+pointers extension only provides the necessary basis for modal
+programming, specific features of languages corresponding to concrete
+modal logics must be implemented as libraries. The `modal-programming`
+package provides support for writing such libraries.
 
 
 Modal logics and modal programming languages

modal-programming.cabal

@@ -16,14 +16,13 @@ description:        Haskell 2010 extended with higher-rank polymorphism is
                     intuitionistic higher-order propositional logic via a
                     Curry–Howard isomorphism. GHC’s static pointers extension,
                     while having been conceived specifically for distributed
-                    programming, further extends Haskell such that it becomes a
-                    kind of generic modal programming language. This allows
-                    programmers to write libraries that turn Haskell into the
-                    Curry–Howard correspondents of various modal logics and to
-                    combine these libraries to arrive at programming languages
-                    that integrate multiple modal features. The
-                    @modal-programming@ package provides support for writing
-                    such libraries.
+                    programming, makes it possible to turn Haskell into the
+                    Curry–Howard correspondents of typical modal logics. Since
+                    the static pointers extension only provides the necessary
+                    basis for modal programming, specific features of languages
+                    corresponding to concrete modal logics must be implemented
+                    as libraries. The @modal-programming@ package provides
+                    support for writing such libraries.
 category:           Control, Effect, Type System
 tested-with:        GHC == { 8.10.7, 9.2.3 }
 extra-source-files: README.md CHANGELOG.md CONTRIBUTING.md

src/Control/Modal.hs

@@ -3,13 +3,12 @@
     System F/ω/ and thus roughly corresponds to intuitionistic higher-order
     propositional logic via a Curry–Howard isomorphism. GHC’s static pointers
     extension, while having been conceived specifically for distributed
-    programming, further extends Haskell such that it becomes a kind of generic
-    modal programming language. This allows programmers to write libraries that
-    turn Haskell into the Curry–Howard correspondents of various modal logics
-    and to combine these libraries to arrive at programming languages that
-    integrate multiple modal features. The @Control.Modal@ module provides
-    support for writing such libraries.
-
+    programming, makes it possible to turn Haskell into the Curry–Howard
+    correspondents of typical modal logics. Since the static pointers extension
+    only provides the necessary basis for modal programming, specific features
+    of languages corresponding to concrete modal logics must be implemented as
+    libraries. The @Control.Modal@ module provides support for writing such
+    libraries.
 
     = Modal logics and modal programming languages