I wrote such an interpreter though the code is quite ugly due to my
lack of experience in the field as well as with Haskell... It took me
the better part of two hour but mainly because I didn't use Parsec
before this. I would of course be happy of any suggestion to amend it
but a plain rewriting
There was more than some bugs, and a lack of strictness that led to
a stack overflow for high values of x... So here is a better version
(not quite there still, but better).
--
Jedaï
{-# OPTIONS -fbang-patterns -funbox-strict-fields #-}
module Minim (Statement (..), Test (..), Program (..), Expr
On Saturday 21 July 2007 01:41:58 Hugh Perkins wrote:
Ok, that got the variables working.
...
Don't fizzle out on me now: this was just getting interesting! :-)
--
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
OCaml for Scientists
http://www.ffconsultancy.com/products/ocaml_for_scientists/?e
heh! well everyone was busy working on icfp or something, so the newsgroup
was pretty dead :-) And I played with opengl a little, which gave better
results than I thought, but not good enough to pursue, and the whole program
was in imperative dos anyway, so I couldnt quite see what was the point
Anyone care to code up a Haskell implementation of this trivial interpreter
for comparison:
http://groups.google.co.uk/group/comp.lang.lisp/browse_frm/thread/7b1ab36f5d5cce0a/0ca59e0bfb794e07?hl=en#0ca59e0bfb794e07
--
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
OCaml for Scientists
Newbie question: why does the following give Not in scope 'c' for the last
line?
string :: Parsec.Parser String
string = do c - Parsec.letter
do cs - string
return c:cs
Parsec.| return [c]
(This is copied more or less rote from
On Fri, Jul 20, 2007 at 10:10:58PM +0200, Hugh Perkins wrote:
Newbie question: why does the following give Not in scope 'c' for the last
line?
I assume you meant
string :: Parsec.Parser String
string = do c - Parsec.letter
do cs - string
return c:cs
Kindof vaguely made a start on this, but cant quite see how to handle
variables.
I guess variables can be stored as a (Map.Map String Double), at least for a
first draft?
Then, I'm building up two hierarchies in parallel:
- a set of parsec functions to parse the incoming string into a Program
Hugh Perkins wrote:
That works just fine as long as the only thing eval has to cope with
is print statements (so eval has type IO ()), but I'm guessing the
clean solution is to thread a Map.Map through that somehow?
You could do that but your code starts to become messy and you'll hit
other
Ok, that got the variables working.
Example:
*Minim evaluateprog $ ProgramTree ( ProgramLeaf $ AssignmentStatement(
VarAssignment (Variable test) ( ValueFromConstant (Constant 3 (
PrintStatement (PrintValue( ValueFromVariable(Variable test
3.0
3.0
I'm having eval return the IO monad,
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