Function wows
Robert Perren
rjp02u@Cs.Nott.AC.UK
Thu, 6 Mar 2003 00:50:41 -0000
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As part of a larger program I have created the following functions to
convert a list of bits into the integer represents, also to simplify
things the order of the bits is reversed [1,1,0,1] represents 1011 (or
13). At the moment the frombin function below works fine.
type Bit = Int
frombin :: [Bit] -> Int
frombin xs = sum (tonum xs)
tonum :: [Bit] -> [Bit]
tonum [] = []
tonum (n:ns) = (n:(tonum (map (*2) ns)))
However why when I try the function below does it not work in Hugs?
frombin :: [Bit] -> Int
frombin [] = 0
frombin (n:ns) = sum (n:( frombin (map (*2) ns)))
Is this surely not just a combination of the two?
Any help would be much appreciated
Thanks,
Rob
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<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>As part of a larger program I have created the =
following
functions to convert a list of bits into the integer represents, also to
simplify things the order of the bits is reversed [1,1,0,1] represents =
1011 (or
13). At the moment the frombin function below works fine. =
</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>type Bit =3D Int</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>frombin :: [Bit] -> Int</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>frombin xs =3D sum (tonum xs)</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>tonum :: [Bit] -> [Bit]</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>tonum [] =3D []</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>tonum (n:ns) =3D (n:(tonum (map (*2) =
ns)))</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>However why when I try the function below does it not =
work
in Hugs?</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>frombin :: [Bit] -> Int</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>frombin [] =3D 0</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>frombin (n:ns) =3D sum (n:( frombin (map (*2) =
ns)))</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Is this surely not just a combination of the =
two?</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Any help would be much appreciated</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Thanks,</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Rob</span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'> </span></font></p>
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font-family:Arial'> </span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
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font-family:Arial'> </span></font></p>
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