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69 lines
2.1 KiB
Plaintext
69 lines
2.1 KiB
Plaintext
import data.matrix.notation
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import data.vector2
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/-!
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Helpers that don't currently fit elsewhere...
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-/
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lemma split_eq {m n : Type*} (x : m × n) (p p' : m × n) :
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p = x ∨ p' = x ∨ (x ≠ p ∧ x ≠ p') := by tauto
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-- For `playfield`s, the piece type and/or piece index type.
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variables (X : Type*)
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variables [has_repr X]
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namespace chess.utils
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section repr
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/--
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An auxiliary wrapper for `option X` that allows for overriding the `has_repr` instance
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for `option`, and rather, output just the value in the `some` and a custom provided
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`string` for `none`.
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-/
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structure option_wrapper :=
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(val : option X)
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(none_s : string)
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instance wrapped_option_repr : has_repr (option_wrapper X) :=
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⟨λ ⟨val, s⟩, (option.map has_repr.repr val).get_or_else s⟩
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variables {X}
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/--
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Construct an `option_wrapper` term from a provided `option X` and the `string`
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that will override the `has_repr.repr` for `none`.
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-/
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def option_wrap (val : option X) (none_s : string) : option_wrapper X := ⟨val, none_s⟩
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-- The size of the "vectors" for a `fin n' → X`, for `has_repr` definitions
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variables {m' n' : ℕ}
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/--
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For a "vector" `X^n'` represented by the type `Π n' : ℕ, fin n' → X`, where
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the `X` has a `has_repr` instance itself, we can provide a `has_repr` for the "vector".
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This definition is used for displaying rows of the playfield, when it is defined
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via a `matrix`, likely through notation.
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-/
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def vec_repr : Π {n' : ℕ}, (fin n' → X) → string :=
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λ _ v, string.intercalate ", " ((vector.of_fn v).to_list.map repr)
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instance vec_repr_instance : has_repr (fin n' → X) := ⟨vec_repr⟩
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/--
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For a `matrix` `X^(m' × n')` where the `X` has a `has_repr` instance itself,
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we can provide a `has_repr` for the matrix, using `vec_repr` for each of the rows of the matrix.
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This definition is used for displaying the playfield, when it is defined
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via a `matrix`, likely through notation.
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-/
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def matrix_repr : Π {m' n'}, matrix (fin m') (fin n') X → string :=
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λ _ _ M, string.intercalate ";\n" ((vector.of_fn M).to_list.map repr)
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instance matrix_repr_instance :
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has_repr (matrix (fin n') (fin m') X) := ⟨matrix_repr⟩
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end repr
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end chess.utils
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