Simple haskell string manage

Question

Theres is a little problem I want to solve with Haskell: let substitute a function that change all of the wildcards in a string for one concrete parameter. The function has de signature of:

subs :: String -> String -> String -> String
-- example:
-- subs 'x' "x^3 + x + sin(x)" "6.2" will generate
--          "6.2^3 + 6.2 + sin(6.2)"

Answer 1

You could use the Text.Regex package.

Your example might look something like this:

import Text.Regex(mkRegex, subRegex)

subs :: String -> String -> String -> String
subs wildcard input value = subRegex (mkRegex wildcard) input value