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-rw-r--r--src/Grasp/Types/IP.hs47
1 files changed, 47 insertions, 0 deletions
diff --git a/src/Grasp/Types/IP.hs b/src/Grasp/Types/IP.hs
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+++ b/src/Grasp/Types/IP.hs
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+module Grasp.Types.IP (
+ IP,
+
+ singleton,
+ empty,
+ isEmpty,
+ peek,
+ push,
+ pop,
+ shift
+ ) where
+
+
+
+
+import Grasp.Types.GNode( GNode )
+
+
+
+
+newtype IP = IP [GNode]
+ deriving (Eq, Show)
+
+
+
+
+singleton :: GNode -> IP
+singleton n = IP [n]
+
+empty :: IP
+empty = IP []
+
+isEmpty :: IP -> Bool
+isEmpty (IP p) = (length p == 0)
+
+peek :: IP -> Maybe GNode
+peek (IP p) = if (length p == 0) then Nothing else Just (head p)
+
+push :: GNode -> IP -> IP
+push n (IP p) = IP (n:p)
+
+pop :: IP -> IP
+pop (IP p) = if (length p == 0) then empty else IP (tail p)
+
+shift :: GNode -> IP -> IP
+shift n (IP p) = if (length p == 0) then empty else IP (n:(tail p))
+