• Top
  • Documentation
  • Books
  • Boolean-reasoning
  • Projects
  • Debugging
  • Std
  • Proof-automation
  • Macro-libraries
  • ACL2
  • Interfacing-tools
  • Hardware-verification
  • Software-verification
    • Kestrel-books
      • Crypto-hdwallet
      • Apt
      • Error-checking
      • Fty-extensions
      • Isar
      • Kestrel-utilities
      • Set
      • Soft
      • C
      • Bv
      • Imp-language
        • Semantics
          • Step
          • Write-var
          • Outcome
          • Beval
          • Read-var
          • Config
          • Terminatingp
          • Aeval
          • Step*
          • Stepn
          • Env
        • Abstract-syntax
        • Interpreter
      • Event-macros
      • Java
      • Bitcoin
      • Ethereum
      • Yul
      • Zcash
      • ACL2-programming-language
      • Prime-fields
      • Json
      • Syntheto
      • File-io-light
      • Cryptography
      • Number-theory
      • Lists-light
      • Axe
      • Builtins
      • Solidity
      • Helpers
      • Htclient
      • Typed-lists-light
      • Arithmetic-light
    • X86isa
    • Axe
    • Execloader
  • Math
  • Testing-utilities

• Semantics

Write-var

Write a variable's value to the environment.

Signature

(write-var var val env) → new-env

Arguments

var — Guard (stringp var).

val — Guard (integerp val).

env — Guard (envp env).

Returns

new-env — Type (envp new-env).

We add/overwrite a/the pair for the variable in the omap. We do this even if the value is 0; in this case, we could instead just remove the pair, since read-var treats an absent variable the same way as one with value 0. But we prefer to always add/overwrite the pair, avoiding any ``normalization'' of the environment (i.e. avoiding insisting that no variable in the environment has value 0). Treating an absent variable as one with value 0 is a mere convenience for having a total read-var.

Definitions and Theorems

Function: write-var

(defun write-var (var val env)
  (declare (xargs :guard (and (stringp var)
                              (integerp val)
                              (envp env))))
  (omap::update (str-fix var)
                (ifix val)
                (env-fix env)))

Theorem: envp-of-write-var

(defthm envp-of-write-var
  (b* ((new-env (write-var var val env)))
    (envp new-env))
  :rule-classes :rewrite)

Theorem: write-var-of-str-fix-var

(defthm write-var-of-str-fix-var
  (equal (write-var (str-fix var) val env)
         (write-var var val env)))

Theorem: write-var-streqv-congruence-on-var

(defthm write-var-streqv-congruence-on-var
  (implies (acl2::streqv var var-equiv)
           (equal (write-var var val env)
                  (write-var var-equiv val env)))
  :rule-classes :congruence)

Theorem: write-var-of-ifix-val

(defthm write-var-of-ifix-val
  (equal (write-var var (ifix val) env)
         (write-var var val env)))

Theorem: write-var-int-equiv-congruence-on-val

(defthm write-var-int-equiv-congruence-on-val
  (implies (acl2::int-equiv val val-equiv)
           (equal (write-var var val env)
                  (write-var var val-equiv env)))
  :rule-classes :congruence)

Theorem: write-var-of-env-fix-env

(defthm write-var-of-env-fix-env
  (equal (write-var var val (env-fix env))
         (write-var var val env)))

Theorem: write-var-env-equiv-congruence-on-env

(defthm write-var-env-equiv-congruence-on-env
  (implies (env-equiv env env-equiv)
           (equal (write-var var val env)
                  (write-var var val env-equiv)))
  :rule-classes :congruence)