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Primitive-narrowing-conversions

Double-to-char

Narrowing conversion from double to char [JLS14:5.1.3].

Signature
(double-to-char operand) → result
Arguments: operand — Guard (double-valuep operand).
Returns: result — Type (char-valuep result).

Definitions and Theorems

Function: double-to-char

(defun double-to-char (operand)
  (declare (xargs :guard (double-valuep operand)))
  (b* ((x (double-value->double operand)))
    (char-value (double-to-char-abs x))))

Theorem: char-valuep-of-double-to-char

(defthm char-valuep-of-double-to-char
  (b* ((result (double-to-char operand)))
    (char-valuep result))
  :rule-classes :rewrite)

Theorem: double-to-char-of-double-value-fix-operand

(defthm double-to-char-of-double-value-fix-operand
  (equal (double-to-char (double-value-fix operand))
         (double-to-char operand)))

Theorem: double-to-char-double-value-equiv-congruence-on-operand

(defthm double-to-char-double-value-equiv-congruence-on-operand
  (implies (double-value-equiv operand operand-equiv)
           (equal (double-to-char operand)
                  (double-to-char operand-equiv)))
  :rule-classes :congruence)