Func.hs

module Calculator.Evaluator.Func where

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import Calculator.Prim.Base (Number)
import Calculator.Prim.Cmd (Cmd(Func))
import Calculator.Prim.Expr (addVar, Bindings, Expr(Constant))
import Calculator.Evaluator.Expr (evalExpr)

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mkFun :: Bindings -> Cmd -> (Number -> Number)
mkFun b (Func _ x e) = \v -> case evalExpr (addVar (x, v) b) e of
                               Constant z -> z
                               _          -> error "Invalid Result"
mkFun _ _            = error "Making function from invalid cmd"

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