I have a beginner question about pattern matching.
I'm trying to learn Elm from OCaml. playing around with math expressions.
How would I pattern match against any Expression x in the example below?
type Expression
= Const Int
| Mul (Expression Expression)
calculate : Expression -> Expression
calculate expr =
case expr of
Mul(Const 1 ,* x*) -> *x*
Mul(*x*, Const 1 ) -> *x*
_ -> expr
I get a bunch of these errors, :
-- TYPE MISMATCH
--------------------------------------------------------------- This tuple
is causing problems in this pattern match. 13| Mul(x, Const 1 ) -> x
^^^^^^^^^^^^^ The pattern matches things of type: ( a, b ) But the values
it will actually be trying to match are: Expression Expression
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