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Make where (for let-where) error out in incorrect position
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‎CHANGELOG.md‎

Lines changed: 9 additions & 1 deletion
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@@ -20,7 +20,15 @@ The same applies if you need the macro parts of `unpythonic` (i.e. import anythi
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- **Python 3.8 and 3.9 support added.**
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23-
- Robustness: several auxiliary syntactic constructs such as `local[]`/`delete[]` (for `do[]`), `call_cc[]` (for `with continuations`), `it` (for `aif[]`), `with expr`/`with block` (for `with let_syntax`/`with abbrev`), and `q`/`u`/`kw` (for `with prefix`) now detect *at macro expansion time* if they appear outside any valid lexical context, and raise `SyntaxError` (with a descriptive message) if so. Previously these constructs could only raise an error at run time, and not all of them could detect the error even then.
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- Robustness: several auxiliary syntactic constructs now detect *at macro expansion time* if they appear outside any valid lexical context, and raise `SyntaxError` (with a descriptive message) if so.
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- The full list is:
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- `call_cc[]`, for `with continuations`
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- `it`, for `aif[]`
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- `local[]`/`delete[]`, for `do[]`
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- `q`/`u`/`kw`, for `with prefix`
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- `where`, for `let[body, where(k0=v0, ...)]` (also for `letseq`, `letrec`, `let_syntax`, `abbrev`)
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- `with expr`/`with block`, for `with let_syntax`/`with abbrev`
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- Previously these constructs could only raise an error at run time, and not all of them could detect the error even then.
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- `with namedlambda` now understands the walrus operator, too. In the construct `f := lambda ...: ...`, the lambda will get the name `f`. (Python 3.8 and later.)
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‎unpythonic/dialects/lispython.py‎

Lines changed: 2 additions & 1 deletion
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@@ -29,14 +29,15 @@ def transform_ast(self, tree): # tree is an ast.Module
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__lang__ = "Lispython" # noqa: F841, just provide it to user code.
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from unpythonic.syntax import (macros, tco, autoreturn, # noqa: F401, F811
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multilambda, quicklambda, namedlambda, f,
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where,
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let, letseq, letrec,
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dlet, dletseq, dletrec,
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blet, bletseq, bletrec,
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local, delete, do, do0,
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let_syntax, abbrev,
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cond)
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# Auxiliary syntax elements for the macros.
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from unpythonic.syntax import where, block, expr # noqa: F401, F811
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from unpythonic.syntax import block, expr # noqa: F401, F811
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from unpythonic import cons, car, cdr, ll, llist, nil, prod, dyn # noqa: F401, F811
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with autoreturn, quicklambda, multilambda, tco, namedlambda:
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__paste_here__ # noqa: F821, just a splicing marker.

‎unpythonic/dialects/pytkell.py‎

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Original file line numberDiff line numberDiff line change
@@ -18,13 +18,14 @@ def transform_ast(self, tree): # tree is an ast.Module
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with q as template:
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__lang__ = "Pytkell" # noqa: F841, just provide it to user code.
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from unpythonic.syntax import (macros, lazy, lazyrec, lazify, autocurry, # noqa: F401, F811
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where,
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let, letseq, letrec,
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dlet, dletseq, dletrec,
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blet, bletseq, bletrec,
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local, delete, do, do0,
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cond, forall)
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# Auxiliary syntax elements for the macros.
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from unpythonic.syntax import where, insist, deny # noqa: F401
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from unpythonic.syntax import insist, deny # noqa: F401
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# Functions that have a haskelly feel to them.
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from unpythonic import (foldl, foldr, scanl, scanr, # noqa: F401
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s, imathify, gmathify, frozendict,

‎unpythonic/dialects/tests/test_listhell.py‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,8 +7,7 @@
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from ...syntax import macros, test # noqa: F401
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from ...test.fixtures import session, testset
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from ...syntax import macros, let, local, delete, do # noqa: F401, F811
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from ...syntax import where # for let-where # noqa: F401
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from ...syntax import macros, let, where, local, delete, do # noqa: F401, F811
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from unpythonic import foldr, cons, nil, ll
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def runtests():

‎unpythonic/syntax/__init__.py‎

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@@ -69,8 +69,6 @@
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# If the line `tree = expander.visit(tree)` is omitted, the macro expands outside-in.
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# Note this default is different from MacroPy's!
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# TODO: Move `where` from letdoutil to letdo, make it a @namemacro, and declare it public.
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# TODO: Consider reversing the MRO of @generic (to latest first), since the point is to be extensible.
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# TODO: Add docs navigation to all documentation files, like `mcpyrate` has.
@@ -101,7 +99,6 @@
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from .lambdatools import * # noqa: F401, F403
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from .lazify import * # noqa: F401, F403
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from .letdo import * # noqa: F401, F403
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from .letdoutil import where # noqa: F401
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from .letsyntax import * # noqa: F401, F403
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from .nb import * # noqa: F401, F403
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from .prefix import * # noqa: F401, F403

‎unpythonic/syntax/letdo.py‎

Lines changed: 19 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,8 @@
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# -*- coding: utf-8 -*-
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"""Local bindings (let), imperative code in expression position (do)."""
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4-
__all__ = ["let", "letseq", "letrec",
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__all__ = ["where",
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"let", "letseq", "letrec",
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"dlet", "dletseq", "dletrec",
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"blet", "bletseq", "bletrec",
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"local", "delete", "do", "do0"]
@@ -30,7 +31,7 @@
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from mcpyrate.quotes import macros, q, u, n, a, t, h # noqa: F401
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from mcpyrate import gensym, parametricmacro
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from mcpyrate import gensym, namemacro, parametricmacro
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from mcpyrate.quotes import capture_as_macro, is_captured_value
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from mcpyrate.walkers import ASTTransformer, ASTVisitor
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@@ -85,6 +86,22 @@ def _destructure_and_apply_let(tree, args, macro_expander, let_transformer, allo
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# --------------------------------------------------------------------------------
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# Macro interface - expr macros
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@namemacro
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def where(tree, *, syntax, **kw):
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"""[syntax, special] `where` operator for let.
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Usage::
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let[body, where((k0, v0), ...)]
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Only meaningful for declaring the bindings in a let-where, for all
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expression-form let constructs: `let`, `letseq`, `letrec`, `let_syntax`,
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`abbrev`.
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"""
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if syntax != "name":
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raise SyntaxError("where (unpythonic.syntax.letdo.where) is a name macro only") # pragma: no cover
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raise SyntaxError("where() is only meaningful in a let[body, where((k0, v0), ...)]") # pragma: no cover
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@parametricmacro
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def let(tree, *, args, syntax, expander, **kw):
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"""[syntax, expr] Introduce expression-local variables.

‎unpythonic/syntax/letdoutil.py‎

Lines changed: 1 addition & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,7 @@
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# -*- coding: utf-8 -*-
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"""Detect let and do forms, and destructure them writably."""
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4-
__all__ = ["where",
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"canonize_bindings", # used by the macro interface layer
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__all__ = ["canonize_bindings", # used by the macro interface layer
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"isenvassign", "islet", "isdo",
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"UnexpandedEnvAssignView", "UnexpandedLetView", "UnexpandedDoView",
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"ExpandedLetView", "ExpandedDoView"]
@@ -16,10 +15,6 @@
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from .astcompat import getconstant, Str
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from .nameutil import isx, getname
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def where(*bindings):
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"""[syntax] Only meaningful in a let[body, where((k0, v0), ...)]."""
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raise RuntimeError("where() is only meaningful in a let[body, where((k0, v0), ...)]") # pragma: no cover
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letf_name = "letter" # must match what ``unpythonic.syntax.letdo._let_expr_impl`` uses in its output.
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dof_name = "dof" # name must match what ``unpythonic.syntax.letdo.do`` uses in its output.
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currycall_name = "currycall" # output of ``unpythonic.syntax.curry``

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