Haskell append to a list conditionally -

i have 2 lists trying fill items. while reading stdin, depending on value of 1 of things read, want append different list. example,

import control.monad(replicatem)  main =     n <- getline     let l1 = [], l2 = []         in replicatem (read n) (getline >>= (\line ->             case line of "yes" ->                 -- line                 -- , append value of thing l1                           "no" ->                 -- else                 -- append value l2             putstrln line)) 

i realise above code has syntax errors , such, can see trying , suggest something.

this answer came with

while @ it, can explain why gives me infinite list:

let g = [] let g = 1:g -- g contains infinite list of 1's 

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this came with:

import control.monad(replicatem) import data.either  geteither::[string] -> [either double double] geteither [] = [] geteither (line:rest) = let [n, h] = words line                             fn = read f :: double                             e = case heist of "yes" -> left fn                                               "no"  -> right fn                             in e : geteither rest  main =     n <- getline     lines <- replicatem (read n) getline     let tup = partitioneithers $ geteither lines :: ([double], [double])     print tup 

not sure how fmap have been used in instance

here short ghci session may give ideas:

> :m + control.monad data.either > partitioneithers <$> replicatem 3 readln :: io ([int], [bool]) left 5 right true left 7 ([5,7],[true]) 

the answer second question let recursive; 2 gs in let g = 1:g referring same in-memory object.