Merge pull request #82 from purescript/more-gen

Enhance string & char generation

Author: garyb

src/Data/Char/Gen.purs

@@ -2,8 +2,9 @@ module Data.Char.Gen where
 
 import Prelude
 
-import Control.Monad.Gen (class MonadGen, chooseInt)
+import Control.Monad.Gen (class MonadGen, chooseInt, oneOf)
 import Data.Char as C
+import Data.NonEmpty ((:|))
 
 -- | Generates a character of the Unicode basic multilingual plain.
 genUnicodeChar :: forall m. MonadGen m => m Char
@@ -20,3 +21,15 @@ genAsciiChar' = C.fromCharCode <$> chooseInt 0 127
 -- | Generates a character that is a numeric digit.
 genDigitChar :: forall m. MonadGen m => m Char
 genDigitChar = C.fromCharCode <$> chooseInt 48 57
+
+-- | Generates a character from the basic latin alphabet.
+genAlpha :: forall m. MonadGen m => m Char
+genAlpha = oneOf (genAlphaLowercase :| [genAlphaUppercase])
+
+-- | Generates a lowercase character from the basic latin alphabet.
+genAlphaLowercase :: forall m. MonadGen m => m Char
+genAlphaLowercase = C.fromCharCode <$> chooseInt 97 122
+
+-- | Generates an uppercase character from the basic latin alphabet.
+genAlphaUppercase :: forall m. MonadGen m => m Char
+genAlphaUppercase = C.fromCharCode <$> chooseInt 65 90

src/Data/String/Gen.purs

@@ -2,14 +2,16 @@ module Data.String.Gen where
 
 import Prelude
 
-import Control.Monad.Gen (class MonadGen, unfoldable)
+import Control.Monad.Gen (class MonadGen, chooseInt, unfoldable, sized, resize)
 import Control.Monad.Rec.Class (class MonadRec)
 import Data.Char.Gen as CG
 import Data.String as S
 
 -- | Generates a string using the specified character generator.
 genString :: forall m. MonadRec m => MonadGen m => m Char -> m String
-genString = map S.fromCharArray <<< unfoldable
+genString genChar = sized \size -> do
+  newSize <- chooseInt 1 size
+  resize (const newSize) $ S.fromCharArray <$> unfoldable genChar
 
 -- | Generates a string using characters from the Unicode basic multilingual
 -- | plain.