insert package:snap-core

Insert a key-value pair into the headers map. If the key already exists in the map, the values are catenated with ", ". Example:

ghci> :set -XOverloadedStrings
ghci> let hdrs = H.insert "Accept" "text/plain" $ H.empty
ghci> hdrs
H {unH = [("accept","text/plain")]}
ghci> H.insert "Accept" "text/html" $ hdrs
H {unH = [("accept","text/plain,text/html")]}

Insert a key-value pair into the headers map, without checking whether the header already exists. The key must be already case-folded, or none of the lookups will work! Example:

ghci> :set -XOverloadedStrings
ghci> let hdrs = H.unsafeInsert "accept" "text/plain" $ H.empty
ghci> hdrs
H {unH = [("accept","text/plain")]}
ghci> let hdrs' = H.unsafeInsert "accept" "text/html" $ hdrs
ghci> hdrs'
H {unH = [("accept","text/html"), ("accept","text/plain")]}
ghci> H.lookup "accept" hdrs'
Just "text/html"