type conversion between alias types

A matrix type is defined as

alias type = DType.float32

struct Matrix[rows: Int, cols: Int]:
    var data: DTypePointer[type]

    @staticmethod
    fn rand() -> Self:
        var data = DTypePointer[type].alloc(rows * cols)
        rand(data, rows * cols)
        return Self(data)

alias type = DType.float32

struct Matrix[rows: Int, cols: Int]:
    var data: DTypePointer[type]

    @staticmethod
    fn rand() -> Self:
        var data = DTypePointer[type].alloc(rows * cols)
        rand(data, rows * cols)
        return Self(data)

Then a Logits type is defined with Matrix with only 1 column:

struct Logits[rows: Int]:
    alias LogitsM = Matrix[rows, 1]
    var logits: Self.LogitsM
    fn __init__(inout self):
        self.logits.__init__()
    @staticmethod
    fn rand() -> Self:
        return Self.LogitsM.rand()

struct Logits[rows: Int]:
    alias LogitsM = Matrix[rows, 1]
    var logits: Self.LogitsM
    fn __init__(inout self):
        self.logits.__init__()
    @staticmethod
    fn rand() -> Self:
        return Self.LogitsM.rand()

Got compile error:

error: Expression [20]:9:33: cannot implicitly convert 'Matrix[rows, 1]' value to 'Logits[rows]' in return value
        return Self.LogitsM.rand()
               ~~~~~~~~~~~~~~~~~^~
expression failed to parse (no further compiler diagnostics)

error: Expression [20]:9:33: cannot implicitly convert 'Matrix[rows, 1]' value to 'Logits[rows]' in return value
        return Self.LogitsM.rand()
               ~~~~~~~~~~~~~~~~~^~
expression failed to parse (no further compiler diagnostics)

1 Reply

Ryulord•7mo ago

LogitsM is a Matrix and you're calling its rand method, which will return a value of type Matrix but the rand method on Logits says it returns a value of type Logits (Self) so you need to convert from Matrix to Logits and it can't do that implicitly. You'll need to write an init method to create Logits from a Matrix

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type conversion between alias types