diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@
 
 A simple commandline text prompt library for user input.
 
+The `SimplePrompt` module provides:
+
 - `prompt`: returns a string
 - `promptNonEmpty` prompts for non-empty string
 - `promptInitial` with pre-filled initial input
@@ -12,3 +14,9 @@
 - `yesNoDefault` [y/N] or [Y/n]
 
 It uses haskeline to read the input.
+
+The `SimplePrompt.Internal` module provides lower-level access to
+functional haskeline InputT monad transformer-based prompt functions:
+
+- `runPrompt`, `getPrompt*`
+- `untilInput`, `mapInput`, `timedInput`, `nonEmptyInput`.
diff --git a/simple-prompt.cabal b/simple-prompt.cabal
--- a/simple-prompt.cabal
+++ b/simple-prompt.cabal
@@ -1,10 +1,11 @@
 name:                simple-prompt
-version:             0.2.0
+version:             0.2.0.1
 synopsis:            Simple commandline text prompt functions
 description:
         The library provides prompt functions for reading user input:
-        prompt returns the input given, prompt_ ignores the input,
-        and yesno asks for confirmation.
+        for example `prompt` returns the input given,
+        `promptEnter` expects only Enter,
+        and `yesNo` asks for confirmation.
 license:             BSD3
 license-file:        LICENSE
 author:              Jens Petersen <juhpetersen@gmail.com>
@@ -16,6 +17,7 @@
 build-type:          Simple
 extra-doc-files:     README.md
                      ChangeLog.md
+extra-source-files:  src/monadconstraint.h
 cabal-version:       2.0
 tested-with:         GHC == 8.6.5
                      || == 8.8.4
diff --git a/src/monadconstraint.h b/src/monadconstraint.h
new file mode 100644
--- /dev/null
+++ b/src/monadconstraint.h
@@ -0,0 +1,5 @@
+#if MIN_VERSION_haskeline(0,8,0)
+#define MONADCONSTRAINT (MonadIO m, MonadMask m)
+#else
+#define MONADCONSTRAINT MonadException m
+#endif