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In this changelog, we document "large-ish" changes to Iris that affect even the way the logic is used on paper. We also document changes in the Coq development; every API-breaking change should be listed, but not every new lemma.

Iris 3.4.0

The highlights and most notable changes of this release are as follows:

  • Coq 8.13 is now supported; the old Coq 8.9 and Coq 8.10 are not supported any more.
  • The new view RA construction generalizes auth to user-defined abstraction relations. (thanks to Gregory Malecha for the inspiration)
  • The new dfrac RA extends frac (fractions 0 < q ≀ 1) with support for "discarding" some part of the fraction in exchange for a persistent witness that discarding has happened. This can be used to easily generalize fractional permissions with support for persistently owning "any part" of the resource. (by Simon Friis Vindum)
  • The new gmap_view RA provides convenient lemmas for ghost ownership of heap-like structures with an "authoritative" view. Thanks to dfrac, it supports both exclusive (mutable) and persistent (immutable) ownership of individual map elements.
  • With this release we are beginning to provide logic-level abstractions for ghost state, which have the advantage that the user does not have to directly interact with RAs to use them.
    • ghost_var provides a logic-level abstraction of ghost variables: a mutable "variable" with fractional ownership.
    • mono_nat provides a "monotone counter" with a persistent witnesses representing a lower bound of the current counter value. (by Tej Chajed)
    • gset_bij provides a monotonically growing partial bijection; this is useful in particular when building binary logical relations for languages with a heap.
  • HeapLang provides a persistent read-only points-to assertion l ↦░ v. (by Simon Friis Vindum)
  • We split Iris into multiple opam packages: coq-iris no longer contains HeapLang, which is now in a separate package coq-iris-heap-lang. The two packages coq-iris-deprecated (for old modules that we eventually plan to remove entirely) and coq-iris-staging (for new modules that are not yet ready for prime time) exist only as development versions, so they are not part of this release.
  • The proofmode now does a better job at picking reasonable names when moving variables into the Coq context without a name being explicitly given by the user. However, the exact variable names remain unspecified. (by Tej Chajed)

Further details are given in the changelog below.

This release of Iris was managed by Ralf Jung and Robbert Krebbers, with contributions by Arthur Azevedo de Amorim, Dan Frumin, Enrico Tassi, Hai Dang, Michael Sammler, Paolo G. Giarrusso, Rodolphe Lepigre, Simon Friis Vindum, Tej Chajed, and Yusuke Matsushita. Thanks a lot to everyone involved!

Changes in algebra:

  • Add constructions to define a camera through restriction of the validity predicate (iso_cmra_mixin_restrict) and through an isomorphism (iso_cmra_mixin).
  • Add a frac_agree library which encapsulates frac * agree A for some OFE A, and provides some useful lemmas.
  • Add the view camera view, which generalizes the authoritative camera auth by being parameterized by a relation that relates the authoritative element with the fragments.
  • Add the camera of discardable fractions dfrac. This is a generalization of the normal fractional camera. See algebra.dfrac for further information.
  • Add gmap_view, a camera providing a "view of a gmap". The authoritative element is any gmap; the fragment provides fractional ownership of a single key, including support for persistent read-only ownership through dfrac. See algebra.lib.gmap_view for further information.
  • Add mono_nat, a wrapper for auth max_nat. The result is an authoritative nat where a fragment is a lower bound whose ownership is persistent. See algebra.lib.mono_nat for further information.
  • Add the gset_bij resource algebra for monotone partial bijections. See algebra.lib.gset_bij for further information.
  • Rename agree_op_inv' β†’ to_agree_op_inv, agree_op_invL' β†’ to_agree_op_inv_L, and add to_agree_op_invN.
  • Rename auth_auth_frac_op_invL β†’ auth_auth_frac_op_inv_L, excl_auth_agreeL β†’ excl_auth_agree_L, frac_auth_agreeL β†’ frac_auth_agree_L, and ufrac_auth_agreeL β†’ ufrac_auth_agree_L.
  • Fix direction of auth_auth_validN to make it consistent with similar lemmas, e.g., auth_auth_valid. The direction is now βœ“{n} (● a) ↔ βœ“{n} a.
  • Rename auth_both_valid to auth_both_valid_discrete and auth_both_frac_valid to auth_both_frac_valid_discrete. The old name is used for new, stronger lemmas that do not assume discreteness.
  • Redefine the authoritative camera in terms of the view camera. As part of this change, we have removed lemmas that leaked implementation details. Hence, the only way to construct elements of auth is via the elements ●{q} a and β—― b. The constructor Auth, and the projections auth_auth_proj and auth_frag_proj no longer exist. Lemmas that referred to these constructors have been removed, in particular: auth_equivI, auth_validI, auth_included, auth_valid_discrete, and auth_both_op. For validity, use auth_auth_valid*, auth_frag_valid*, or auth_both_valid* instead.
  • Rename auth_update_core_id into auth_update_frac_alloc.
  • Rename cmra_monotone_valid into cmra_morphism_valid (this rename was forgotten in !56).
  • Move the *_validI and *_equivI lemmas to a new module, base_logic.algebra. That module is exported by base_logic.base_logic so it should usually be available everywhere without further changes.
  • The authoritative fragment βœ“ (β—― b : auth A) is no longer definitionally equal to βœ“ b.
  • Change *_valid lemma statements involving fractions to use Qp addition and inequality instead of RA composition and validity (also in base_logic and the higher layers).
  • Move algebra.base module to prelude.prelude.
  • Strengthen cmra_op_discrete to assume only βœ“{0} (x1 β‹… x2) instead of βœ“ (x1 β‹… x2).
  • Rename the types ofeTβ†’ofe, cmraTβ†’cmra, ucmraTβ†’ucmra, and the constructors OfeTβ†’Ofe, CmraTβ†’Cmra, and UcmraTβ†’Ucmra since the T suffix is not needed. This change makes these names consistent with bi, which also does not have a T suffix.
  • Rename typeclass instances of CMRA operational typeclasses (Op, Core, PCore, Valid, ValidN, Unit) to have a _instance suffix, so that their original names are available to use as lemma names.
  • Rename frac_valid'β†’frac_valid, frac_op'β†’frac_op, ufrac_op'β†’ufrac_op, coPset_op_union β†’ coPset_op, coPset_core_self β†’ coPset_core, gset_op_union β†’ gset_op, gset_core_self β†’ gset_core, gmultiset_op_disj_union β†’ gmultiset_op, gmultiset_core_empty β†’ gmultiset_core, nat_op_plus β†’ nat_op, max_nat_op_max β†’ max_nat_op. Those names were previously blocked by typeclass instances.

Changes in bi:

  • Add big op lemmas big_op{L,L2,M,M2,S}_intuitionistically_forall and big_sepL2_forall, big_sepMS_forall, big_sepMS_impl, and big_sepMS_dup.
  • Add lemmas to big-ops that provide ownership of a single element and permit changing the quantified-over predicate when re-assembling the big-op: big_sepL_lookup_acc_impl, big_sepL2_lookup_acc_impl, big_sepM_lookup_acc_impl, big_sepM2_lookup_acc_impl, big_sepS_elem_of_acc_impl, big_sepMS_elem_of_acc_impl.
  • Add lemmas big_sepM_filter' and big_sepM_filter matching the corresponding big_sepS lemmas.
  • Add lemmas for big-ops of magic wands: big_sepL_wand, big_sepL2_wand, big_sepM_wand, big_sepM2_wand, big_sepS_wand, big_sepMS_wand.
  • Add notation Β¬ P for P β†’ False to bi_scope.
  • Add fupd_mask_intro which can be conveniently iApplyed to goals of the form |={E1,E2}=> to get rid of the fupd in the goal if E2 βŠ† E1. The lemma fupd_mask_weaken Enew can be iApplyed to shrink the first mask to Enew without getting rid of the modality; the same effect can also be obtained slightly more conveniently by using iMod with fupd_mask_subseteq Enew. To make the new names work, rename some existing lemmas: fupd_intro_mask β†’ fupd_mask_intro_subseteq, fupd_intro_mask' β†’ fupd_mask_subseteq (implicit arguments also changed here), fupd_mask_weaken β†’ fupd_mask_intro_discard. Remove fupd_mask_same since it was unused and obscure. In the BiFUpd axiomatization, rename bi_fupd_mixin_fupd_intro_mask to bi_fupd_mixin_fupd_mask_subseteq and weaken the lemma to be specifically about emp (the stronger version can be derived).
  • Remove bi.tactics with tactics that predate the proofmode (and that have not been working properly for quite some time).
  • Strengthen persistent_sep_dup to support propositions that are persistent and either affine or absorbing.
  • Fix the statement of the lemma fupd_plainly_laterN; the old lemma was a duplicate of fupd_plain_laterN.
  • Strengthen big_sepL2_app_inv by weakening a premise (it is sufficient for one of the two pairs of lists to have equal length).
  • Rename equiv_entails β†’ equiv_entails_1_1, equiv_entails_sym β†’ equiv_entails_1_2, and equiv_spec β†’ equiv_entails.
  • Remove the laws pure_forall_2 : (βˆ€ a, ⌜ Ο† a ⌝) ⊒ ⌜ βˆ€ a, Ο† a ⌝ from the BI interface and factor it into a type class BiPureForall.

Changes in proofmode:

  • The proofmode now preserves user-supplied names for existentials when using iDestruct ... as (?) "...". This is backwards-incompatible if you were relying on the previous automatic names (which were always "H", possibly freshened). It also requires some changes if you were implementing IntoExist yourself, since the typeclass now forwards names. If your instance transforms one IntoExist into another, you can generally just forward the name from the premise.
  • The proofmode also preserves user-supplied names in iIntros, for example with iIntros (?) and iIntros "%", as described for destructing existentials above. As part of this change, it now uses a base name of H for pure facts rather than the previous default of a. This also requires some changes if you were implementing FromForall, in order to forward names.
  • Make iFrame "less" smart w.r.t. clean up of modalities. It now consistently removes the modalities <affine>, <absorbing>, <persistent> and β–‘ only if the result after framing is True or emp. In particular, it no longer removes <affine> if the result after framing is affine, and it no longer removes β–‘ if the result after framing is intuitionistic.
  • Allow framing below an <affine> modality if the hypothesis that is framed is affine. (Previously, framing below <affine> was only possible if the hypothesis that is framed resides in the intuitionistic context.)
  • Add Coq side-condition Ο† to class ElimAcc (similar to what we already had for ElimInv and ElimModal).
  • Add a tactic iSelect pat tac (similar to select in std++) which runs the tactic tac H with the name H of the last hypothesis of the intuitionistic or spatial context matching pat. The tactic iSelect is used to implement:
    • iRename select (pat)%I into name which renames the matching hypothesis,
    • iDestruct select (pat)%I as ... which destructs the matching hypothesis,
    • iClear select (pat)%I which clears the matching hypothesis,
    • iRevert select (pat)%I which reverts the matching hypothesis,
    • iFrame select (pat)%I which cancels the matching hypothesis.

Changes in base_logic:

  • Add a ghost_var library that provides (fractional) ownership of a ghost variable of arbitrary Type.
  • Define a ghost state library on top of the mono_nat resource algebra. See base_logic.lib.mono_nat for further information.
  • Define a ghost state library on top of the gset_bij resource algebra. See base_logic.lib.gset_bij for further information.
  • Extend the gen_heap library with read-only points-to assertions using discardable fractions.
    • The mapsto connective now takes a dfrac rather than a frac (i.e., positive rational number Qp).
    • The notation l ↦{ dq } v is generalized to discardable fractions dq : dfrac.
    • The new notation l ↦{# q} v is used for a concrete fraction q : frac (e.g., to enable writing l ↦{# 1/2} v).
    • The new notation l ↦░ v is used for the discarded fraction. This persistent proposition provides read-only access to l.
    • The lemma mapsto_persist : l ↦{dq} v ==βˆ— l ↦░ v is used for making the location l read-only.
    • See the changes to HeapLang for an indication on how to adapt your language.
    • See the changes to iris-examples for an indication on how to adapt your development. In particular, instead of βˆƒ q, l ↦{q} v you likely want to use l ↦░ v, which has the advantage of being persistent (rather than just duplicable).
  • Change type of some ghost state lemmas (mostly about allocation) to use βˆ— instead of ∧ (consistent with our usual style). This affects the following lemmas: own_alloc_strong_dep, own_alloc_cofinite_dep, own_alloc_strong, own_alloc_cofinite, own_updateP, saved_anything_alloc_strong, saved_anything_alloc_cofinite, saved_prop_alloc_strong, saved_prop_alloc_cofinite, saved_pred_alloc_strong, saved_pred_alloc_cofinite, auth_alloc_strong, auth_alloc_cofinite, auth_alloc.
  • Change uPred_mono to only require inclusion at the smaller step-index.
  • Put iProp/iPreProp-isomorphism into the own construction. This affects clients that define higher-order ghost state constructions. Concretely, when defining an inG, the functor no longer needs to be applied to iPreProp, but should be applied to iProp. This avoids clients from having to push through the iProp/iPreProp-isomorphism themselves, which is now handled once and for all by the own construction.
  • Rename gen_heap_ctx to gen_heap_interp, since it is meant to be used in the state interpretation of WP and since _ctx is elsewhere used as a suffix indicating "this is a persistent assumption that clients should always have in their context". Likewise, rename proph_map_ctx to proph_map_interp.
  • Move uPred.prod_validI, uPred.option_validI, and uPred.discrete_fun_validI to the new base_logic.algebra module. That module is exported by base_logic.base_logic so these names are now usually available everywhere, and no longer inside the uPred module.
  • Remove the gen_heap notations l ↦ - and l ↦{q} -. They were barely used and looked very confusing in context: l ↦ - βˆ— P looks like a magic wand.
  • Change gen_inv_heap notation l ↦░ I to l ↦_I β–‘, so that ↦░ can be used by gen_heap.
  • Strengthen mapsto_valid_2 conclusion from βœ“ (q1 + q2)%Qp to βŒœβœ“ (q1 + q2)%Qp ∧ v1 = v2⌝.
  • Change gen_heap_init to also return ownership of the points-to facts for the initial heap.
  • Rename mapsto_mapsto_ne to mapsto_frac_ne, and add a simpler mapsto_ne that does not require reasoning about fractions.
  • Deprecate the auth and sts modules. These were logic-level wrappers around the underlying RAs; as far as we know, they are unused since they were not flexible enough for practical use.
  • Deprecate the viewshift module, which defined a binary view-shift connective with an implicit persistence modality. It was unused and too easily confused with ={_}=βˆ—, the binary view-shift (fancy update) without a persistence modality.

Changes in program_logic:

  • wp_strong_adequacy now applies to an initial state with multiple threads instead of only a single thread. The derived adequacy lemmas are unchanged.
  • pure_exec_fill is no longer registered as an instance for PureExec, to avoid TC search attempting to apply this instance all the time.
  • Merge wp_value_inv/wp_value_inv' into wp_value_fupd/wp_value_fupd' by making the lemmas bidirectional.
  • Generalize HeapLang's mapsto (↦), array (β†¦βˆ—), and atomic heap connectives to discardable fractions. See the CHANGELOG entry in the category base_logic for more information.
  • Opening an invariant or eliminating a mask-changing update modality around a non-atomic weakest precondition creates a side-condition Atomic .... Before, this would fail with the unspecific error "iMod: cannot eliminate modality (|={E1,E2}=> ...) in (WP ...)".
  • In Ectx_step and step_atomic, mark the parameters that are determined by the goal as implicit.
  • Deprecate the hoare module to prevent accidental usage; the recommended way to write Hoare-style specifications is to use Texan triples.

Changes in heap_lang:

  • wp_pures now turns goals of the form WP v {{ Ξ¦ }} into Ξ¦ v.
  • Fix wp_bind in case of a NOP (i.e., when the given expression pattern is already at the top level).
  • The wp_ tactics now preserve the possibility of doing a fancy update when the expression reduces to a value.
  • Move IntoVal, AsVal, Atomic, AsRecV, and PureExec instances to their own file heap_lang.class_instances.
  • Move inv_head_step tactic and head_step auto hints (now part of new hint database head_step) to heap_lang.tactics.
  • The tactic wp_apply no longer performs wp_pures before applying the given lemma. The new tactic wp_smart_apply repeatedly performs single wp_pure steps until the lemma matches the goal.

The following sed script helps adjust your code to the renaming (on macOS, replace sed by gsed, installed via e.g. brew install gnu-sed). Note that the script is not idempotent, do not run it twice.

sed -i -E -f- $(find theories -name "*.v") <<EOF
# agree and L suffix renames
s/\bagree_op_inv'/to_agree_op_inv/g
s/\bagree_op_invL'/to_agree_op_inv_L/g
s/\bauth_auth_frac_op_invL\b/auth_auth_frac_op_inv_L/g
s/\b(excl|frac|ufrac)_auth_agreeL/\1_auth_agree_L/g
# auth_both_valid
s/\bauth_both_valid\b/auth_both_valid_discrete/g
s/\bauth_both_frac_valid\b/auth_both_frac_valid_discrete/g
# gen_heap_ctx and proph_map_ctx
s/\bgen_heap_ctx\b/gen_heap_interp/g
s/\bproph_map_ctx\b/proph_map_interp/g
# other gen_heap changes
s/\bmapsto_mapsto_ne\b/mapsto_frac_ne/g
# remove Ts in algebra
s/\bofeT\b/ofe/g
s/\bOfeT\b/Ofe/g
s/\bcmraT\b/cmra/g
s/\bCmraT\b/Cmra/g
s/\bucmraT\b/ucmra/g
s/\bUcmraT\b/Ucmra/g
# _op/valid/core lemmas
s/\b(u?frac_(op|valid))'/\1/g
s/\b((coPset|gset)_op)_union\b/\1/g
s/\b((coPset|gset)_core)_self\b/\1/g
s/\b(gmultiset_op)_disj_union\b/\1/g
s/\b(gmultiset_core)_empty\b/\1/g
s/\b(nat_op)_plus\b/\1/g
s/\b(max_nat_op)_max\b/\1/g
# equiv_spec
s/\bequiv_entails\b/equiv_entails_1_1/g
s/\bequiv_entails_sym\b/equiv_entails_1_2/g
s/\bequiv_spec\b/equiv_entails/g
EOF

Iris 3.3.0 (released 2020-07-15)

This release does not have any outstanding highlights, but contains a large number of improvements all over the board. For instance:

  • heap_lang now supports deallocation as well as better reasoning about "invariant locations" (locations that perpetually satisfy some Coq-level invariant).
  • Invariants (inv N P) are more flexible, now also supporting splitting and merging of invariants with respect to separating conjunction.
  • Performance of the proofmode for BIs constructed on top of other BIs (e.g., monPred) was greatly improved, leading to up to 70% speedup in individual files. As part of this refactoring, the proofmode can now also be instantiated with entirely "logical" notion of BIs that do not have a (non-trivial) metric structure, and still support reasoning about β–·.
  • The proof mode now provides experimental support for naming pure facts in intro patterns. See iris/string-ident for details.
  • Iris now provides official ASCII notation. We still recommend using the Unicode notation for better consistency and interoperability with other Iris libraries, but provide ASCII notation for when Unicode is not an option.
  • We removed several coercions, fixing "ambiguous coercion path" warnings and solving some readability issues.
  • Coq 8.10, 8.11, and 8.12 are newly supported by this release, and Coq 8.7 and 8.8 are no longer supported.

Further details are given in the changelog below. We always first list the potentially breaking changes, then (some of) the additions.

This release of Iris received contributions by Abel Nieto, Amin Timany, Dan Frumin, Derek Dreyer, Dmitry Khalanskiy, Gregory Malecha, Jacques-Henri Jourdan, Jonas Kastberg, Jules Jacobs, Matthieu Sozeau, Maxime Dénès, Michael Sammler, Paolo G. Giarrusso, Ralf Jung, Robbert Krebbers, Simon Friis Vindum, Simon Spies, and Tej Chajed. Thanks a lot to everyone involved!

Changes in heap_lang:

  • Remove global Open Scope Z_scope from heap_lang.lang, and leave it up to reverse dependencies if they want to Open Scope Z_scope or not.

  • Fix all binary operators performing pointer arithmetic (instead of just the dedicated OffsetOp operator doing that).

  • Rename heap_lang.lifting to heap_lang.primitive_laws. There now also exists heap_lang.derived_laws.

  • Make lemma names for fill more consistent

    • Use the _inv suffix for the the backwards directions: reducible_fill β†’ reducible_fill_inv, reducible_no_obs_fill β†’ reducible_no_obs_fill_inv, not_stuck_fill β†’ not_stuck_fill_inv.
    • Use the non-_inv names (that freed up) for the forwards directions: reducible_fill, reducible_no_obs_fill, irreducible_fill_inv.

  • Remove namespace N from is_lock.

  • Add support for deallocation of locations via the Free operation.

  • Add a fraction to the heap_lang array assertion.

  • Add lib.array module for deallocating, copying and cloning arrays.

  • Add TWP (total weakest-pre) lemmas for arrays.

  • Add a library for "invariant locations": heap locations that will not be deallocated (i.e., they are GC-managed) and satisfy some pure, Coq-level invariant. See iris.base_logic.lib.gen_inv_heap for details.

  • Add the ghost state for "invariant locations" to heapG. This affects the statement of heap_adequacy, which is now responsible for initializing the "invariant locations" invariant.

  • Add lemma mapsto_mapsto_ne : Β¬ βœ“(q1 + q2)%Qp β†’ l1 ↦{q1} v1 -βˆ— l2 ↦{q2} v2 -βˆ— ⌜l1 β‰  l2⌝.

  • Add lemma is_lock_iff and show that is_lock is contractive.

Changes in program_logic:

  • In the axiomatization of ectx languages, replace the axiom of positivity of context composition with an axiom that says if fill K e takes a head step, then either K is the empty evaluation context or e is a value.

Changes in the logic (base_logic, bi):

  • Rename some accessor-style lemmas to consistently use the suffix _acc instead of _open: inv_open β†’ inv_acc, inv_open_strong β†’ inv_acc_strong, inv_open_timeless β†’ inv_acc_timeless, na_inv_open β†’ na_inv_acc, cinv_open β†’ cinv_acc, cinv_open_strong β†’ cinv_acc_strong, auth_open β†’ auth_acc, sts_open β†’ sts_acc. To make this work, also rename inv_acc β†’ inv_alter. (Most developments should be unaffected as the typical way to invoke these lemmas is through iInv, and that does not change.)

  • Change inv_iff, cinv_iff and na_inv_iff to make order of arguments consistent and more convenient for iApply. They are now of the form inv N P -βˆ— β–· β–‘ (P ↔ Q) -βˆ— inv N Q and (similar for na_inv_iff and cinv_iff), following e.g., inv_alter and wp_wand.

  • Rename inv_sep_1 β†’ inv_split_1, inv_sep_2 β†’ inv_split_2, and inv_sep β†’ inv_split to be consistent with the naming convention in boxes.

  • Update the strong variant of the accessor lemma for cancellable invariants to match that of regular invariants, where you can pick the mask at a later time. (The other part that makes it strong is that you get back the token for the invariant immediately, not just when the invariant is closed again.)

  • Rename iProp/iPreProp to iPropO/iPrePropO since they are ofeTs. Introduce iProp for the Type carrier of iPropO.

  • Flatten the BI hierarchy by merging the bi and sbi canonical structures. This gives significant performance benefits on developments that construct BIs from BIs (e.g., use monPred). For, example it gives a performance gain of 37% overall on lambdarust-weak, with improvements for individual files up to 72%, see Iris issue #303. The concrete changes are as follows:

    • The sbi canonical structure has been removed.
    • The bi canonical structure contains the later modality. It does not require the later modality to be contractive or to satisfy the LΓΆb rule, so we provide a smart constructor bi_later_mixin_id to get the later axioms "for free" if later is defined to be the identity function.
    • There is a separate class BiLΓΆb, and a "free" instance of that class if the later modality is contractive. A BiLΓΆb instance is required for the iLΓΆb tactic, and for timeless instances of implication and wand.
    • There is a separate type class BiInternalEq for BIs with a notion of internal equality (internal equality was part of sbi). An instance of this class is needed for the iRewrite tactic, and the various lemmas about internal equality.
    • The class SbiEmbed has been removed and been replaced by classes BiEmbedLater and BiEmbedInternalEq.
    • The class BiPlainly has been generalized to BIs without internal equality. As a consequence, there is a separate class BiPropExt for BIs with propositional extensionality (i.e., β–  (P βˆ—-βˆ— Q) ⊒ P ≑ Q).
    • The class BiEmbedPlainly is a bi-entailment (i.e., βŽ‘β–  P⎀ ⊣⊒ β–  ⎑P⎀ instead of β–  ⎑P⎀ ⊒ βŽ‘β–  P⎀) as it has been generalized to BIs without a internal equality. In the past, the left-to-right direction was obtained for "free" using the rules of internal equality.

  • Remove coercion from iProp (and other MoSeL propositions) to Prop. Instead, use the new unary notation ⊒ P, or ⊒@{PROP} P if the proposition type cannot be inferred. This also means that %I should not be necessary any more when stating lemmas, as P above is automatically parsed in scope %I.

  • Some improvements to the bi/lib/core construction:

    • Rename coreP_wand into coreP_entails since it does not involve wands.
    • Generalize coreP_entails to non-affine BIs, and prove more convenient version coreP_entails' for coreP P with P affine.
    • Add instance coreP_affine P : Affine P β†’ Affine (coreP P) and lemma coreP_wand P Q : <affine> β–  (P -βˆ— Q) -βˆ— coreP P -βˆ— coreP Q.

  • Remove notation for 3-mask step-taking updates, and made 2-mask notation less confusing by distinguishing it better from mask-changing updates. Old: |={Eo,Ei}β–·=> P. New: |={Eo}[Ei]β–·=> P. Here, Eo is the "outer mask" (used at the beginning and end) and Ei the "inner mask" (used around the β–· in the middle). As part of this, the lemmas about the 3-mask variant were changed to be about the 2-mask variant instead, and step_fupd_mask_mono now also has a more consistent argument order for its masks.

  • Add a counterexample showing that sufficiently powerful cancellable invariants with a linear token subvert the linearity guarantee (see bi.lib.counterexmples for details).

  • Redefine invariants as "semantic invariants" so that they support splitting and other forms of weakening.

  • Add lemmas inv_combine and inv_combine_dup_l for combining invariants.

  • Add the type siProp of "plain" step-indexed propositions, together with basic proofmode support.

  • New ASCII versions of Iris notations. These are marked parsing only and can be made available using Require Import iris.bi.ascii. The new notations are (notations marked [†] are disambiguated using notation scopes):

    • entailment: |- for ⊒ and -|- for ⊣⊒
    • logic[†]: -> for β†’, /\\ for ∧, \\/ for ∨, and <-> for ↔
    • quantifiers[†]: forall for βˆ€ and exists for βˆƒ
    • separation logic: ** for βˆ—, -* for -βˆ—, and *-* for βˆ—-βˆ—
    • step indexing: |> for β–·
    • modalities: <#> for β–‘ and <except_0> for β—‡
    • most derived notations can be computed from previous notations using the substitutions above, e.g. replace βˆ— with * and β–· with |>. Examples include the following:
      • |={E1,E2}=* P for |={E1,E2}=βˆ—
      • P ={E}=* Q for P ={E}=βˆ— Q
      • P ={E1,E2}=* Q for P ={E1,E2}=βˆ— Q
      • |={E1}[E2]|>=> Q for |={E1}[E2]β–·=> Q The full list can be found in theories/bi/ascii.v, where the ASCII notations are defined in terms of the unicode notations.

  • Add affine, absorbing, persistent and timeless instances for telescopes.

  • Add a construction bi_rtc to create reflexive transitive closures of PROP-level binary relations.

  • Slightly strengthen the lemmas big_sepL_nil', big_sepL2_nil', big_sepM_nil' big_sepM2_empty', big_sepS_empty', and big_sepMS_empty'. They now only require that the argument P is affine instead of the whole BI being affine.

  • Add big_sepL_insert_acc, a variant of big_sepL_lookup_acc which allows updating the value.

  • Add many missing Proper/non-expansiveness lemmas for big-ops.

  • Add big_*_insert_delete lemmas to split a <[i:=x]> m map into i and the rest.

  • Seal the definitions of big_opS, big_opMS, big_opM and big_sepM2 to prevent undesired simplification.

  • Fix big_sepM2_fmap* only working for nat keys.

Changes in proofmode:

  • Make use of notypeclasses refine in the implementation of iPoseProof and iAssumption, see https://gitlab.mpi-sws.org/iris/iris/merge_requests/329. This has two consequences:

    1. Coq's "new" unification algorithm (the one in refine, not the "old" one in apply) is used more often by the proof mode tactics.
    2. Due to the use of notypeclasses refine, TC constraints are solved less eagerly, see coq/coq#6583. In order to port your development, it is often needed to instantiate evars explicitly (since TC search is performed less eagerly), and in few cases it is needed to unfold definitions explicitly (due to new unification algorithm behaving differently).

  • Strengthen the tactics iDestruct, iPoseProof, and iAssert:

    • They succeed in certain cases where they used to fail.
    • They keep certain hypotheses in the intuitionistic context, where they were moved to the spatial context before. The latter can lead to stronger proof mode contexts, and therefore to backwards incompatibility. This can usually be fixed by manually clearing some hypotheses. A more detailed description of the changes can be found in https://gitlab.mpi-sws.org/iris/iris/merge_requests/341.

  • Remove the long-deprecated cofeT alias (for ofeT) and dec_agree RA (use agree instead).

  • Add auto hint for βˆ—-βˆ—.

  • Add new tactic iStopProof to turn the proof mode entailment into an ordinary Coq goal big star of context ⊒ proof mode goal.

  • Add new introduction pattern -# pat that moves a hypothesis from the intuitionistic context to the spatial context.

  • The tactic iAssumption also recognizes assumptions ⊒ P in the Coq context.

  • Better support for telescopes in the proof mode, i.e., all tactics should recognize and distribute telescopes now.

  • The proof mode now supports names for pure facts in intro patterns. Support requires implementing string_to_ident. Without this tactic such patterns will fail. We provide one implementation using Ltac2 which works with Coq 8.11 and can be installed with opam; see iris/string-ident for details.

Changes in algebra:

  • Remove Core type class for defining the total core; it is now always defined in terms of the partial core. The only user of this type class was the STS RA.

  • The functions {o,r,ur}Functor_diag are no longer coercions, and renamed into {o,r,ur}Functor_apply to better match their intent. This fixes "ambiguous coercion path" warnings.

  • Rename {o,r,ur}Functor_{ne,id,compose,contractive} into {o,r,ur}Functor_map_{ne,id,compose,contractive}.

  • Move derived camera constructions (frac_auth and ufrac_auth) to the folder algebra/lib.

  • Rename mnat to max_nat and "box" it by creating a separate type for it.

  • Move the RAs for nat and positive and the mnat RA into a separate module. They must now be imported from From iris.algebra Require Import numbers.

  • Make names of f_op/f_core rewrite lemmas more consistent by always making _core/_op the suffix: op_singleton β†’ singleton_op, core_singleton β†’ singleton_core, discrete_fun_op_singleton β†’ discrete_fun_singleton_op, discrete_fun_core_singleton β†’ discrete_fun_singleton_core, list_core_singletonM β†’ list_singleton_core, list_op_singletonM β†’ list_singleton_op, sts_op_auth_frag β†’ sts_auth_frag_op, sts_op_auth_frag_up β†’ sts_auth_frag_up_op, sts_op_frag β†’ sts_frag_op, list_op_length β†’ list_length_op, list_core_singletonM β†’ list_singletonM_core, list_op_singletonM β†’ list_singletonM_op.

  • All list "map singleton" lemmas consistently use singletonM in their name: list_singleton_valid β†’ list_singletonM_valid, list_singleton_core_id β†’ list_singletonM_core_id, list_singleton_snoc β†’ list_singletonM_snoc, list_singleton_updateP β†’ list_singletonM_updateP, list_singleton_updateP' β†’ list_singletonM_updateP', list_singleton_update β†’ list_singletonM_update, list_alloc_singleton_local_update β†’ list_alloc_singletonM_local_update.

  • Remove auth_both_op and rename auth_both_frac_op into auth_both_op.

  • Add lemma singleton_included : {[ i := x ]} β‰Ό ({[ i := y ]} ↔ x ≑ y ∨ x β‰Ό y, and rename existing asymmetric lemmas (with a singleton on just the LHS): singleton_includedN β†’ singleton_includedN_l, singleton_included β†’ singleton_included_l, singleton_included_exclusive β†’ singleton_included_exclusive_l.

  • Add notion ofe_iso A B that states that OFEs A and B are isomorphic. This is used in the COFE solver.

  • Add {o,r,ur}Functor_oFunctor_compose for composition of functors.

  • Add pair_op_1 and pair_op_2 to split a pair where one component is the unit.

  • Add derived camera construction excl_auth A for auth (option (excl A)).

  • Make lemma Excl_included a bi-implication.

  • Make auth_update_core_id work with any fraction of the authoritative element.

  • Add min_nat, an RA for natural numbers with min as the operation.

  • Add many missing Proper/non-expansiveness lemmas for maps and lists.

  • Add list_singletonM_included and list_lookup_singletonM_{lt,gt} lemmas about singletons in the list RA.

  • Add list_core_id', a stronger version of list_core_id which only talks about elements that are actually in the list.

The following sed script helps adjust your code to the renaming (on macOS, replace sed by gsed, installed via e.g. brew install gnu-sed). Note that the script is not idempotent, do not run it twice.

sed -i -E '
# functor renames
s/\b(o|r|ur)Functor_(ne|id|compose|contractive)\b/\1Functor_map_\2/g
# singleton_included renames
s/\bsingleton_includedN\b/singleton_includedN_l/g
s/\bsingleton_included\b/singleton_included_l/g
s/\bsingleton_included_exclusive\b/singleton_included_exclusive_l/g
# f_op/f_core renames
s/\b(op|core)_singleton\b/singleton_\1/g
s/\bdiscrete_fun_(op|core)_singleton\b/discrete_fun_singleton_\1/g
s/\bsts_op_(auth_frag|auth_frag_up|frag)\b/sts_\1_op/g
s/\blist_(op|core)_singletonM\b/list_singletonM_\1/g
s/\blist_op_length\b/list_length_op/g
# list "singleton map" renames
s/\blist_singleton_valid\b/list_singletonM_valid/g
s/\blist_singleton_core_id\b/list_singletonM_core_id/g
s/\blist_singleton_snoc\b/list_singletonM_snoc/g
s/\blist_singleton_updateP\b/list_singletonM_updateP/g
s/\blist_singleton_update\b/list_singletonM_update/g
s/\blist_alloc_singleton_local_update\b/list_alloc_singletonM_local_update/g
# inv renames
s/\binv_sep(|_1|_2)\b/inv_split\1/g
s/\binv_acc\b/inv_alter/g
s/\binv_open(|_strong|_timeless)\b/inv_acc\1/g
s/\bcinv_open(|_strong)\b/cinv_acc\1/g
s/\b(na_inv|auth|sts)_open\b/\1_acc/g
# miscellaneous
s/\bauth_both_frac_op\b/auth_both_op/g
s/\bmnat\b/max_nat/g
s/\bcoreP_wand\b/coreP_entails/g
' $(find theories -name "*.v")

Iris 3.2.0 (released 2019-08-29)

The highlight of this release is the completely re-engineered interactive proof mode. Not only did many tactics become more powerful; the entire proof mode can now be used not just for Iris but also for other separation logics satisfying the proof mode interface (e.g., Iron and GPFSL). Also see the accompanying paper.

Beyond that, the Iris program logic gained the ability to reason about potentially stuck programs, and a significantly strengthened adequacy theorem that unifies the three previously separately presented theorems. There are now also Hoare triples for total program correctness (but with very limited support for invariants) and logical atomicity.

And finally, our example language HeapLang was made more realistic (Compare-and-set got replaced by compare-exchange and limited to only compare values that can actually be compared atomically) and more powerful, with added support for arrays and prophecy variables.

Further details are given in the changelog below.

This release of Iris received contributions by Aleő Bizjak, Amin Timany, Dan Frumin, Glen Mével, Hai Dang, Hugo Herbelin, Jacques-Henri Jourdan, Jan Menz, Jan-Oliver Kaiser, Jonas Kastberg Hinrichsen, Joseph Tassarotti, Mackie Loeffel, Marianna Rapoport, Maxime Dénès, Michael Sammler, Paolo G. Giarrusso, Pierre-Marie Pédrot, Ralf Jung, Robbert Krebbers, Rodolphe Lepigre, and Tej Chajed. Thanks a lot to everyone involved!

Changes in the theory of Iris itself:

  • Change in the definition of WP, so that there is a fancy update between the quantification over the next states and the later modality. This makes it possible to prove more powerful lifting lemmas: The new versions feature an "update that takes a step".
  • Add weakest preconditions for total program correctness.
  • "(Potentially) stuck" weakest preconditions and the "plainly modality" are no longer considered experimental.
  • Add the notion of an "observation" to the language interface, so that every reduction step can optionally be marked with an event, and an execution trace has a matching list of events. Change WP so that it is told the entire future trace of observations from the beginning.
  • The LΓΆb rule is now a derived rule; it follows from later-intro, later being contractive and the fact that we can take fixpoints of contractive functions.
  • Add atomic updates and logically atomic triples, including tactic support. See heap_lang/lib/increment.v for an example.
  • Extend the state interpretation with a natural number that keeps track of the number of forked-off threads, and have a global fixed proposition that describes the postcondition of each forked-off thread (instead of it being True).
  • A stronger adequacy statement for weakest preconditions that involves the final state, the post-condition of forked-off threads, and also applies if the main-thread has not terminated.
  • The user-chosen functor used to instantiate the Iris logic now goes from COFEs to Cameras (it was OFEs to Cameras).

Changes in heap_lang:

  • CAS (compare-and-set) got replaced by CmpXchg (compare-exchange). The difference is that CmpXchg returns a pair consisting of the old value and a boolean indicating whether the comparison was successful and hence the exchange happened. CAS can be obtained by simply projecting to the second component, but also providing the old value more closely models the primitive typically provided in systems languages (C, C++, Rust). The comparison by this operation also got weakened to be efficiently implementable: CmpXchg may only be used to compare "unboxed" values that can be represented in a single machine word. It is sufficient if one of the two compared values is unboxed.
  • For consistency, the restrictions CmpXchg imposes on comparison also apply to the = binary operator. This also fixes the long-standing problem that that operator allowed compared closures with each other.
  • Implement prophecy variables using the new support for "observations". The erasure theorem (showing that prophecy variables do not alter program behavior) can be found in the iris/examples repository.
  • heap_lang now uses right-to-left evaluation order. This makes it significantly easier to write specifications of curried functions.
  • heap_lang values are now injected in heap_lang expressions via a specific constructor of the expr inductive type. This simplifies much the tactical infrastructure around the language. In particular, this allow us to get rid the reflection mechanism that was needed for proving closedness, atomicity and "valueness" of a term. The price to pay is the addition of new "administrative" reductions in the operational semantics of the language.
  • heap_lang now has support for allocating, accessing and reasoning about arrays (continuously allocated regions of memory).
  • One can now assign "meta" data to heap_lang locations.

Changes in Coq:

  • An all-new generalized proof mode that abstracts away from Iris! Major new features:
    • The proof mode can now be used with logics derived from Iris (like iGPS), with non-step-indexed logics and even with non-affine (i.e., linear) logics.
    • iModIntro is more flexible and more powerful, it now also subsumes iNext and iAlways.
    • General infrastructure for deriving a logic for monotone predicates over an existing logic (see the paper for more details). Developments instantiating the proof mode typeclasses may need significant changes. For developments just using the proof mode tactics, porting should not be too much effort. Notable things to port are:
    • All the BI laws moved from the uPred module to the bi module. For example, uPred.later_equivI became bi.later_equivI.
    • Big-ops are automatically imported, imports of iris.base_logic.big_op have to be removed.
    • The ⊒ notation can sometimes infer different (but convertible) terms when searching for the BI to use, which (due to Coq limitations) can lead to failing rewrites, in particular when rewriting at function types.
  • The iInv tactic can now be used without the second argument (the name for the closing update). It will then instead add the obligation to close the invariant to the goal.
  • The new iEval tactic can be used to execute a simplification or rewriting tactic on some specific part(s) of the proofmode goal.
  • Added support for defining derived connectives involving n-ary binders using telescopes.
  • The proof mode now more consistently "prettifies" the goal after each tactic. Prettification also simplifies some BI connectives, like conditional modalities and telescope quantifiers.
  • Improved pretty-printing of Iris connectives (in particular WP and fancy updates) when Coq has to line-wrap the output. This goes hand-in-hand with an improved test suite that also tests pretty-printing.
  • Added a gmultiset RA.
  • Rename timelessP β†’ timeless (projection of the Timeless class)
  • The CMRA axiom cmra_extend is now stated in Type, using sigT instead of in Prop using exists. This makes it possible to define the function space CMRA even for an infinite domain.
  • Rename proof mode type classes for laters:
    • IntoLaterN β†’ MaybeIntoLaterN (this one may strip a later)
    • IntoLaterN' β†’ IntoLaterN (this one should strip a later)
    • IntoLaterNEnv β†’ MaybeIntoLaterNEnv
    • IntoLaterNEnvs β†’ MaybeIntoLaterNEnvs
  • Rename:
    • frag_auth_op β†’ frac_auth_frag_op
    • cmra_opM_assoc β†’ cmra_op_opM_assoc
    • cmra_opM_assoc_L β†’ cmra_op_opM_assoc_L
    • cmra_opM_assoc' β†’ cmra_opM_opM_assoc
  • namespaces has been moved to std++.
  • Changed IntoVal to be directly usable for rewriting e into of_val v, and changed AsVal to be usable for rewriting via the [v <-] destruct pattern.
  • wp_fork is now written in curried form.
  • PureExec/wp_pure now supports taking multiple steps at once.
  • A new tactic, wp_pures, executes as many pure steps as possible, excluding steps that would require unlocking subterms. Every impure wp_ tactic executes this tactic before doing anything else.
  • Add big_sepM_insert_acc.
  • Add big separating conjunctions that operate on pairs of lists (big_sepL2) and on pairs of maps (big_sepM2). In the former case the lists are required to have the same length, and in the latter case the maps are required to have the same domains.
  • The _strong lemmas (e.g. own_alloc_strong) work for all infinite sets, instead of just for cofinite sets. The versions with cofinite sets have been renamed to use the _cofinite suffix.
  • Remove locked value lambdas. The value scope notations rec: f x := e and (Ξ»: x, e) no longer add a locked. Instead, we made the wp_ tactics smarter to no longer unfold lambdas/recs that occur behind definitions.
  • Export the fact that iPreProp is a COFE.
  • The CMRA auth now can have fractional authoritative parts. So now auth has 3 types of elements: the fractional authoritative ●{q} a, the full authoritative ● a ≑ ●{1} a, and the non-authoritative β—― a. Updates are only possible with the full authoritative element ● a, while fractional authoritative elements have agreement: βœ“ (●{p} a β‹… ●{q} b) β‡’ a ≑ b. As a consequence, auth is no longer a COFE and does not preserve Leibniz equality.
  • Add a COFE construction (and functor) on dependent pairs sigTO, dual to discrete_funO.
  • Rename in auth:
    • Use auth_auth_proj/auth_frag_proj for the projections of auth: authoritative β†’ auth_auth_proj and auth_own β†’ auth_frag_proj.
    • Use auth_auth and auth_frag for the injections into authoritative elements and non-authoritative elements respectively.
    • Lemmas for the projections and injections are renamed accordingly. For examples:
      • authoritative_validN β†’ auth_auth_proj_validN
      • auth_own_validN β†’ auth_frag_proj_validN
      • auth_auth_valid was not renamed because it was already used for the authoritative injection.
    • auth_both_valid β†’ auth_both_valid_2
    • auth_valid_discrete_2 β†’ auth_both_valid
  • Add the camera ufrac for unbounded fractions (i.e. without fractions that can be > 1) and the camera ufrac_auth for a variant of the authoritative fractional camera (frac_auth) with unbounded fractions.
  • Changed frac_auth notation from ●!/β—―! to ●F/β—―F. sed script: s/β—―!/β—―F/g; s/●!/●F/g;.
  • Lemma prop_ext works in both directions; its default direction is the opposite of what it used to be.
  • Make direction of f_op rewrite lemmas more consistent: Flip pair_op, Cinl_op, Cinr_op, cmra_morphism_op, cmra_morphism_pcore, cmra_morphism_core.
  • Rename lemmas fupd_big_sep{L,M,S,MS} into big_sep{L,M,S,MS}_fupd to be consistent with other such big op lemmas. Also add such lemmas for bupd.
  • Rename C suffixes into O since we no longer use COFEs but OFEs. Also rename ofe_fun into discrete_fun and the corresponding notation -c> into -d>. The renaming can be automatically done using the following script (on macOS, replace sed by gsed, installed via e.g. brew install gnu-sed):
sed -i '
s/\bCofeMor/OfeMor/g;
s/\-c>/\-d>/g;
s/\bcFunctor/oFunctor/g;
s/\bCFunctor/OFunctor/g;
s/\b\%CF/\%OF/g;
s/\bconstCF/constOF/g;
s/\bidCF/idOF/g
s/\bdiscreteC/discreteO/g;
s/\bleibnizC/leibnizO/g;
s/\bunitC/unitO/g;
s/\bprodC/prodO/g;
s/\bsumC/sumO/g;
s/\bboolC/boolO/g;
s/\bnatC/natO/g;
s/\bpositiveC/positiveO/g;
s/\bNC/NO/g;
s/\bZC/ZO/g;
s/\boptionC/optionO/g;
s/\blaterC/laterO/g;
s/\bofe\_fun/discrete\_fun/g;
s/\bdiscrete\_funC/discrete\_funO/g;
s/\bofe\_morC/ofe\_morO/g;
s/\bsigC/sigO/g;
s/\buPredC/uPredO/g;
s/\bcsumC/csumO/g;
s/\bagreeC/agreeO/g;
s/\bauthC/authO/g;
s/\bnamespace_mapC/namespace\_mapO/g;
s/\bcmra\_ofeC/cmra\_ofeO/g;
s/\bucmra\_ofeC/ucmra\_ofeO/g;
s/\bexclC/exclO/g;
s/\bgmapC/gmapO/g;
s/\blistC/listO/g;
s/\bvecC/vecO/g;
s/\bgsetC/gsetO/g;
s/\bgset\_disjC/gset\_disjO/g;
s/\bcoPsetC/coPsetO/g;
s/\bgmultisetC/gmultisetO/g;
s/\bufracC/ufracO/g
s/\bfracC/fracO/g;
s/\bvalidityC/validityO/g;
s/\bbi\_ofeC/bi\_ofeO/g;
s/\bsbi\_ofeC/sbi\_ofeO/g;
s/\bmonPredC/monPredO/g;
s/\bstateC/stateO/g;
s/\bvalC/valO/g;
s/\bexprC/exprO/g;
s/\blocC/locO/g;
s/\bdec\_agreeC/dec\_agreeO/g;
s/\bgnameC/gnameO/g;
s/\bcoPset\_disjC/coPset\_disjO/g;
' $(find theories -name "*.v")

Iris 3.1.0 (released 2017-12-19)

Changes in and extensions of the theory:

  • Define uPred as a quotient on monotone predicates M -> SProp.
  • Get rid of some primitive laws; they can be derived: True ⊒ β–‘ True and β–‘ (P ∧ Q) ⊒ β–‘ (P βˆ— Q)
  • Camera morphisms have to be homomorphisms, not just monotone functions.
  • Add a proof that f has a fixed point if f^k is contractive.
  • Constructions for least and greatest fixed points over monotone predicates (defined in the logic of Iris using impredicative quantification).
  • Add a proof of the inverse of wp_bind.
  • [Experimental feature] Add new modality: β–  ("plainly").
  • [Experimental feature] Support verifying code that might get stuck by distinguishing "non-stuck" vs. "(potentially) stuck" weakest preconditions. (See [Swasey et al., OOPSLA '17] for examples.) The non-stuck WP e @ E {{ Ξ¦ }} ensures that, as e runs, it does not get stuck. The stuck WP e @ E ?{{ Ξ¦ }} ensures that, as usual, all invariants are preserved while e runs, but it permits execution to get stuck. The former implies the latter. The full judgment is WP e @ s; E {{ Ξ¦ }}, where non-stuck WP uses stuckness bit s = NotStuck while stuck WP uses s = MaybeStuck.

Changes in Coq:

  • Move the prelude folder to its own project: coq-std++
  • Some extensions/improvements of heap_lang:
    • Improve handling of pure (non-state-dependent) reductions.
    • Add fetch-and-add (FAA) operation.
    • Add syntax for all Coq's binary operations on Z.
  • Generalize saved_prop to let the user choose the location of the type-level later. Rename the general form to saved_anything. Provide saved_prop and saved_pred as special cases.
  • Improved big operators:
    • They are no longer tied to cameras, but work on any monoid
    • The version of big operations over lists was redefined so that it enjoys more definitional equalities.
  • Rename some things and change notation:
    • The unit of a camera: empty -> unit, βˆ… -> Ξ΅
    • Disjointness: βŠ₯ -> ##
    • A proof mode type class IntoOp -> IsOp
    • OFEs with all elements being discrete: Discrete -> OfeDiscrete
    • OFE elements whose equality is discrete: Timeless -> Discrete
    • Timeless propositions: TimelessP -> Timeless
    • Camera elements such that core x = x: Persistent -> CoreId
    • Persistent propositions: PersistentP -> Persistent
    • The persistent modality: always -> persistently
    • Adequacy for non-stuck weakestpre: adequate_safe -> adequate_not_stuck
    • Consistently SnakeCase identifiers:
      • CMRAMixin -> CmraMixin
      • CMRAT -> CmraT
      • CMRATotal -> CmraTotal
      • CMRAMorphism -> CmraMorphism
      • CMRADiscrete -> CmraDiscrete
      • UCMRAMixin -> UcmraMixin
      • UCMRAT -> UcmraT
      • DRAMixin -> DraMixin
      • DRAT -> DraT
      • STS -> Sts
    • Many lemmas also changed their name. always_* became persistently_*, and furthermore: (the following list is not complete)
      • impl_wand -> impl_wand_1 (it only involves one direction of the equivalent)
      • always_impl_wand -> impl_wand
      • always_and_sep_l -> and_sep_l
      • always_and_sep_r -> and_sep_r
      • always_sep_dup -> sep_dup
      • wand_impl_always -> impl_wand_persistently (additionally, the direction of this equivalence got swapped for consistency's sake)
      • always_wand_impl -> persistently_impl_wand (additionally, the direction of this equivalence got swapped for consistency's sake) The following sed snippet should get you most of the way (on macOS you will have to replace sed by gsed, installed via e.g. brew install gnu-sed):
sed -i 's/\bPersistentP\b/Persistent/g; s/\bTimelessP\b/Timeless/g; s/\bCMRADiscrete\b/CmraDiscrete/g; s/\bCMRAT\b/CmraT/g; s/\bCMRAMixin\b/CmraMixin/g; s/\bUCMRAT\b/UcmraT/g; s/\bUCMRAMixin\b/UcmraMixin/g; s/\bSTS\b/Sts/g' $(find -name "*.v")
  • PersistentL and TimelessL (persistence and timelessness of lists of propositions) are replaces by TCForall from std++.
  • Fix a bunch of consistency issues in the proof mode, and make it overall more usable. In particular:
    • All proof mode tactics start the proof mode if necessary; iStartProof is no longer needed and should only be used for building custom proof mode tactics.
    • Change in the grammar of specialization patterns: >[...] -> [> ...]
    • Various new specification patterns for done and framing.
    • There is common machinery for symbolic execution of pure reductions. This is provided by the type classes PureExec and IntoVal.
    • There is a new connective tc_opaque, which can be used to make definitions opaque for type classes, and thus opaque for most tactics of the proof mode.
    • Define Many missing type class instances for distributing connectives.
    • Implement the tactics iIntros (?) and iIntros "!#" (i.e. iAlways) using type classes. This makes them more generic, e.g., iIntros (?) also works when the universal quantifier is below a modality, and iAlways also works for the plainness modality. A breaking change, however, is that these tactics now no longer work when the universal quantifier or modality is behind a type class opaque definition. Furthermore, this can change the name of anonymous identifiers introduced with the "%" pattern.
  • Make ofe_fun dependently typed, subsuming iprod. The latter got removed.
  • Define the generic fill operation of the ectxi_language construct in terms of a left fold instead of a right fold. This gives rise to more definitional equalities.
  • The language hierarchy (language, ectx_language, ectxi_language) is now fully formalized using canonical structures instead of using a mixture of type classes and canonical structures. Also, it now uses explicit mixins. The file program_logic/ectxi_language contains some documentation on how to setup Iris for your language.
  • Restore the original, stronger notion of atomicity alongside the weaker notion. These are Atomic a e where the stuckness bit s indicates whether expression e is weakly (a = WeaklyAtomic) or strongly (a = StronglyAtomic) atomic.
  • Various improvements to solve_ndisj.
  • Use Hint Mode to prevent Coq from making arbitrary guesses in the presence of evars, which often led to divergence. There are a few places where type annotations are now needed.
  • The rules internal_eq_rewrite and internal_eq_rewrite_contractive are now stated in the logic, i.e., they are iApply-friendly.

Iris 3.0.0 (released 2017-01-11)

  • There now is a deprecation process. The modules *.deprecated contain deprecated notations and definitions that are provided for backwards compatibility and will be removed in a future version of Iris.
  • View shifts are radically simplified to just internalize frame-preserving updates. Weakestpre is defined inside the logic, and invariants and view shifts with masks are also coded up inside Iris. Adequacy of weakestpre is proven in the logic. The old ownership of the entire physical state is replaced by a user-selected predicate over physical state that is maintained by weakestpre.
  • Use OFEs instead of COFEs everywhere. COFEs are only used for solving the recursive domain equation. As a consequence, CMRAs no longer need a proof of completeness. (The old cofeT is provided by algebra.deprecated.)
  • Implement a new agreement construction. Unlike the old one, this one preserves discreteness. dec_agree is thus no longer needed and has been moved to algebra.deprecated.
  • Renaming and moving things around: uPred and the rest of the base logic are in base_logic, while program_logic is for everything involving the general Iris notion of a language.
  • Renaming in prelude.list: Rename prefix_of -> prefix and suffix_of -> suffix in lemma names, but keep notation l1 `prefix_of` l2 and l1 `suffix_of` l2. l1 `sublist` l2 becomes l1 `sublist_of` l2. Rename contains -> submseteq and change l1 `contains` l2 to l1 βŠ†+ l2.
  • Slightly weaker notion of atomicity: an expression is atomic if it reduces in one step to something that does not reduce further.
  • Changed notation for embedding Coq assertions into Iris. The new notation is βŒœΟ†βŒ. Also removed = and βŠ₯ from the Iris scope. (The old notations are provided in base_logic.deprecated.)
  • Up-closure of namespaces is now a notation (↑) instead of a coercion.
  • With invariants and the physical state being handled in the logic, there is no longer any reason to demand the CMRA unit to be discrete.
  • The language can now fork off multiple threads at once.
  • Local Updates (for the authoritative monoid) are now a 4-way relation with syntax-directed lemmas proving them.

Iris 2.0

  • [heap_lang] No longer use dependent types for expressions. Instead, values carry a proof of closedness. Substitution, closedness and value-ness proofs are performed by computation after reflecting into a term langauge that knows about values and closed expressions.
  • [program_logic/language] The language does not define its own "atomic" predicate. Instead, atomicity is defined as reducing in one step to a value.
  • [program_logic] Due to a lack of maintenance and usefulness, lifting lemmas for Hoare triples are removed.

Iris 2.0-rc2

This version matches the final ICFP 2016 paper.

  • [algebra] Make the core of an RA or CMRA a partial function.
  • [program_logic/lifting] Lifting lemmas no longer round-trip through a user-chosen predicate to define the configurations we can reduce to; they directly relate to the operational semantics. This is equivalent and much simpler to read.

Iris 2.0-rc1

This is the Coq development and Iris Documentation as submitted to ICFP 2016.