GJ% ghci
GHCi, version 8.8.4: https://www.haskell.org/ghc/  :? for help

> import Text.Regex.PCRE
> "abc" =~ "[a-z]{3}"

<interactive>:2:1: error:
    • Non type-variable argument
        in the constraint: RegexContext Regex [Char] target
      (Use FlexibleContexts to permit this)
    • When checking the inferred type
        it :: forall target. RegexContext Regex [Char] target => target

> "abc" =~ "[a-z]{3}" :: Bool
True

> "123 abc 456" =~ "[a-z]{3}" :: Bool
True

> "123 abc 456" =~ "^[a-z]{3}" :: Bool
False

> "abc 456" =~ "^[a-z]{3}" :: Bool
True

> putStr "abc\ndef\n"
abc
def

> putStr "abc\\def\n"
abc\def

> "123 \nabc 456" =~ "^[a-z]{3}" :: Bool
True

> "123 \nabc 456" =~ "\\A[a-z]{3}" :: Bool
False

> "xyz 123 \nabc 456" =~ "\\A[a-z]{3}" :: Bool
True

> "xyz 123 \nabc 456" =~ "\\A[a-z]{3}" :: String
"xyz"

> "123 \nabc 456" =~ "\\A[a-z]{3}" :: String
""

> "789 xyz 123 \nabc 456" =~ "[a-z]{3}" :: (String,String,String)
("789 ","xyz"," 123 \nabc 456")

> "789 xyz 123 \nabc 456" =~ "\\A[a-z]{3}" :: (String,String,String)
("789 xyz 123 \nabc 456","","")

> "789 xyz 123 \nabc 456" =~ "([a-z]{3})" :: (String,String,String,[String])
("789 ","xyz"," 123 \nabc 456",["xyz"])

> "789 xyz 123 \nabc 456" =~ "\\A([a-z]{3})" :: (String,String,String,[String])
("789 xyz 123 \nabc 456","","",[])

> "789xyz123 \nabc 456" =~ "\\A[0-9]+([a-z]{3})[0-9]+" :: (String,String,String,[String])
("","789xyz123"," \nabc 456",["xyz"])

> "789xyz123 \nabc 456" =~ "\\A[0-9]+([a-z]{3})([0-9]+)" :: (String,String,String,[String])
("","789xyz123"," \nabc 456",["xyz","123"])

> ^D
Leaving GHCi.
GJ%