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Base58-character

Base58-character-fix

Fixer for base58-character.

Signature
(base58-character-fix x) → fixed-x
Arguments: x — Guard (base58-characterp x).
Returns: fixed-x — Type (base58-characterp fixed-x).

Definitions and Theorems

Function: base58-character-fix

(defun base58-character-fix (x)
  (declare (xargs :guard (base58-characterp x)))
  (mbe :logic
       (if (base58-characterp x)
           x
         *base58-zero*)
       :exec x))

Theorem: base58-characterp-of-base58-character-fix

(defthm base58-characterp-of-base58-character-fix
  (b* ((fixed-x (base58-character-fix x)))
    (base58-characterp fixed-x))
  :rule-classes :rewrite)

Theorem: base58-character-fix-when-base58-characterp

(defthm base58-character-fix-when-base58-characterp
  (implies (base58-characterp x)
           (equal (base58-character-fix x) x)))

Theorem: characterp-of-base58-character-fix

(defthm characterp-of-base58-character-fix
  (b* ((?fixed-x (base58-character-fix x)))
    (characterp fixed-x))
  :rule-classes :type-prescription)