There's a theory this should work: getContents >>= lines >>> map read >>> sum >>> print But unfortunately we have: `(>>=)' [infixl 1] `(>>>)' [infixr 1] Meaning we must write: getContents >>= (lines >>> map read >>> sum >>> print) Indeed, all Arrow ops are infixr. Are there any technical/compelling reasons for this? -- Don
On Fri, Jul 27, 2007 at 12:08:30AM +1000, Donald Bruce Stewart wrote:
There's a theory this should work:
getContents >>= lines >>> map read >>> sum >>> print
But unfortunately we have:
`(>>=)' [infixl 1] `(>>>)' [infixr 1]
Meaning we must write:
getContents >>= (lines >>> map read >>> sum >>> print)
Indeed, all Arrow ops are infixr. Are there any technical/compelling reasons for this?
Not that I can recall. But it's the precedence rather than the associativity that's bothering you here.
ross:
On Fri, Jul 27, 2007 at 12:08:30AM +1000, Donald Bruce Stewart wrote:
There's a theory this should work:
getContents >>= lines >>> map read >>> sum >>> print
But unfortunately we have:
`(>>=)' [infixl 1] `(>>>)' [infixr 1]
Meaning we must write:
getContents >>= (lines >>> map read >>> sum >>> print)
Indeed, all Arrow ops are infixr. Are there any technical/compelling reasons for this?
Not that I can recall. But it's the precedence rather than the associativity that's bothering you here.
Yes, I suppose it is a vote for 0.5 precedence, if they're not to behave as for >> and >>= ? Which are: infixl 1 >>, >>= So I can write: print 'x' >> getChar >>= ord >>> print -- Don
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Ross Paterson