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<DIV><FONT size=2 face=Arial>In <EM>Learn You a Haskell for Great Good!,</EM>
the author Miran Lipovaca indicates that to understand Monads you need to
know Functors...</FONT></DIV>
<DIV><FONT size=2 face=Arial>So, I noticed the following:</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>class Functor f where</FONT></DIV>
<DIV><FONT size=2 face=Arial> fmap::(a->b)->f a->f b</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>instance Functor [] where</FONT></DIV>
<DIV><FONT size=2 face=Arial> fmap = map</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>map::(a->b)->[a]->[b]</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>if [] is substituted for f in the class definition
of Functor the following is obtained</FONT></DIV>
<DIV><FONT size=2 face=Arial>class Functor [] where</FONT></DIV>
<DIV><FONT size=2 face=Arial> fmap::(a->b)->[]a->[]b</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>my questions are:</FONT></DIV>
<DIV><FONT size=2 face=Arial> 1. is this substitution ok?</FONT></DIV>
<DIV><FONT size=2 face=Arial> 2. is []a = [a]?</FONT></DIV>
<DIV><FONT size=2 face=Arial> 3. is []b = [b]?</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>if 2. and 3. are valid then the following is
obtained:</FONT></DIV>
<DIV><FONT size=2 face=Arial> fmap::(a->b)->[a]->[b]</FONT></DIV>
<DIV><FONT size=2 face=Arial>which is the same as map type and therefore: fmap =
map. QED.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Can you please answer questions 2 and 3
above?</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Thank you</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
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