Haskell print function name

Question

Hello i would like to print the names of functions in a list. Is it somehow possible to do so?

my example:

import Text.Show.Functions
f1 x = if x == 1 then 1 else 0
f2 x = if x == 2 then 1 else 0
f3 x = if x == 1 then 2 else 0
fs = [f1,f2,f3]
fs

writes out [<function>,<function>,<function>] but I want [f1,f2,f3]

Functions don't have names per se; you can bind one or more names to a single function, but the function itself has no notion of which names are bound to it. — chepner
– chepner, Commented Mar 17, 2018 at 15:09

Daniel Wagner · Accepted Answer · 2018-03-17 12:08:43Z

4

No, it is not possible. If you want named functions, you will have to whip them up yourself; e.g.

data Named a = Named { name :: String, val :: a }
instance Show (Named a) where show = name
fs = [Named "f1" f1, Named "f2" f2, Named "f3" f3]

answered Mar 17, 2018 at 12:08

Daniel Wagner

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1 Comment

It might go without saying, but now fs has a type like [Named (a -> b)], not [(a -> b)]. Subsequent code using fs would need to adapt.