Update depending on a column's value with Esqueleto

I want to update a table t having column c1 and c2 by a Haskell function of type fx :: c1 -> c2 now I want to apply this function to my table t and update the values of c2. How I can do this in one run? Like in postgres I will write it as: update t set c2 = fx(c1); What will be the esqueleto equivalent for the same ?