-fill marr# (I# i#, e) next s1# =
- case writeArray# marr# i# e s1# of { s2# ->
- next s2# }
+-- NB: put the \s after the "=" so that 'fill'
+-- inlines when applied to three args
+fill marr# (I# i#, e) next
+ = \s1# -> case writeArray# marr# i# e s1# of
+ s2# -> next s2#