Are there string parsing functions in Daml?

Are there any functions in Daml to go from Text → Optional Decimal for example? If not, is there maybe Haskell code I could use (ie. copy)?

You want DA.Text. In your case parseDecimal does what you want. (Remember you can also use the search function in the docs using type signatures. Search for Text -> Optional Decimal should find this for you!)

Ah right - I was searching for Text -> Decimal and nothing came up. Makes sense, thanks!