fst package:clash-prelude

fst :: (a, b) -> a
clash-prelude Clash.HaskellPrelude
Extract the first component of a pair.
fsToHz :: (HasCallStack, Fractional a) => Femtoseconds -> a
clash-prelude Clash.Signal.Internal
Calculate the frequency in Hz, given the period in fs I.e., to calculate the clock frequency of a clock with a period of 5000 fs: 
>>> fsToHz (Femtoseconds 5000)
2.0e11
NB: This function is not synthesizable