One of the things Menai hasn't had up until now is any concept of records or structs. This has felt a little clunky as it tended to force things into dictionaries or obscure lists.
Yesterday and today this got fixed and now Menai has a struct concept. This allows for structures with named fields and a series of functions that can introspect on structures.
Struct syntax and functions
Struct declaration
(let ((Point (struct (x y)))) ...)Declares a new named struct type. The binding name becomes the type name. Valid as the RHS of let, let*, or letrec.
Construction
(Point 1 2)Call the struct type as a function with positional field values.
Field access
(struct-get p 'x)Functional update
(struct-set p 'x 10)Returns a new struct with the named field changed; all other fields are unchanged.
Equality
(struct=? p1 p2)
(struct!=? p1 p2)True if same type and all fields equal.
Type predicates
(struct? p) ; any struct instance
(struct-type? Point p) ; specific type checkIntrospection
(struct-type-name Point) ; → "Point" (takes a type, not an instance)
(struct-fields Point) ; → ('x 'y) (takes a type, not an instance)
(struct-type p) ; → Point (takes an instance, returns its type)Pattern matching
; Predicate form
(match p ((? (struct-type? Point) p) (struct-get p 'x)) (_ 0))
; Destructuring form — field names bound directly
(match p ((Point x y) (integer+ x y)) (_ 0))Nominality
Two struct types with identical fields are still distinct types:
(let ((Point (struct (x y)))
(Vec (struct (x y)))) ...)Point and Vec are different types.
Hashability
Struct instances are hashable (usable as set members or dict keys) provided all their fields are hashable scalar values.
A comparison
It's always nice to try out a new feature. Claude reviewed various tests and rewrote the Rubik's cube solver to use the struct feature. The result was approximately an 7.5% performance improvement!
The representation of the structure is clearly a better fit for this problem, and the code is more readable!
Old:
✓ Test completed successfully
Result: Solution found! Moves: R' F' D' R U' R'
====================================================================================================
PROFILING RESULTS (Top 80 functions, sorted by cumulative)
====================================================================================================
20414891 function calls (20376286 primitive calls) in 6.781 seconds
Ordered by: cumulative time
List reduced from 360 to 80 due to restriction <80>
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.000 0.000 6.886 6.886 /Users/dave/github/m6r/humbug/src/menai/menai.py:1161(evaluate)
1 0.000 0.000 6.886 6.886 /Users/dave/github/m6r/humbug/src/menai/menai.py:1144(_evaluate_raw)
1 3.339 3.339 6.800 6.800 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:349(execute)
1915766 0.717 0.000 0.798 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:629(_op_call)
115138 0.141 0.000 0.303 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3101(_op_dict_set)
892259 0.253 0.000 0.290 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3221(_op_list_append)
1915767 0.235 0.000 0.235 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:878(_op_return)
554868 0.179 0.000 0.202 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3263(_op_list_rest)
930578 0.200 0.000 0.200 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3310(_op_list_ref)
1960594 0.172 0.000 0.172 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:522(_op_move)
1409026 0.169 0.000 0.169 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:554(_op_jump_if_true)
613723 0.122 0.000 0.146 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3338(_op_list_null_p)
894969 0.134 0.000 0.134 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3247(_op_list_first)
2880815 0.122 0.000 0.122 0.000 {built-in method builtins.len}
1449947 0.112 0.000 0.112 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:485(_op_load_const)
518076 0.106 0.000 0.106 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:1200(_op_integer_neq_p)
320907 0.093 0.000 0.106 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3208(_op_list_prepend)
115147 0.063 0.000 0.097 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_value.py:315(__init__)
135625 0.071 0.000 0.094 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:582(_op_make_closure)
988295 0.088 0.000 0.088 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_value.py:366(to_hashable_key)
1 0.000 0.000 0.086 0.086 /Users/dave/github/m6r/humbug/src/menai/menai_compiler.py:95(compile)
182289 0.053 0.000 0.071 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3139(_op_dict_get)
88278 0.054 0.000 0.058 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:691(_op_tail_call)
191180 0.040 0.000 0.040 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:2502(_op_string_eq_p)
554861 0.033 0.000 0.033 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:532(_op_jump)
76105 0.027 0.000 0.031 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:1298(_op_integer_add)
430690 0.030 0.000 0.030 0.000 {method 'append' of 'list' objects}
136298 0.028 0.000 0.028 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:603(_op_patch_closure)
57564 0.021 0.000 0.026 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3295(_op_list_length)
58202 0.023 0.000 0.025 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3234(_op_list_reverse)
2/1 0.000 0.000 0.024 0.024 /Users/dave/github/m6r/humbug/src/menai/menai_compiler.py:69(compile_to_resolved_ast)
2587/1 0.001 0.000 0.023 0.023 /Users/dave/github/m6r/humbug/src/menai/menai_ast_module_resolver.py:89(resolve)
...New:
Result: Solution found! Moves: R' F' D' R U' R'
====================================================================================================
PROFILING RESULTS (Top 80 functions, sorted by cumulative)
====================================================================================================
18173868 function calls (18137374 primitive calls) in 6.258 seconds
Ordered by: cumulative time
List reduced from 376 to 80 due to restriction <80>
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.000 0.000 6.365 6.365 /Users/dave/github/m6r/humbug/src/menai/menai.py:1161(evaluate)
1 0.000 0.000 6.365 6.365 /Users/dave/github/m6r/humbug/src/menai/menai.py:1144(_evaluate_raw)
1 3.203 3.203 6.281 6.281 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:349(execute)
1723893 0.648 0.000 0.722 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:629(_op_call)
873083 0.250 0.000 0.286 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3221(_op_list_append)
1723894 0.213 0.000 0.213 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:878(_op_return)
545280 0.178 0.000 0.202 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3263(_op_list_rest)
930578 0.195 0.000 0.195 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3310(_op_list_ref)
1409026 0.169 0.000 0.169 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:554(_op_jump_if_true)
1830089 0.165 0.000 0.165 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:522(_op_move)
613723 0.123 0.000 0.147 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3338(_op_list_null_p)
875786 0.132 0.000 0.132 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3247(_op_list_first)
2686868 0.114 0.000 0.114 0.000 {built-in method builtins.len}
320907 0.094 0.000 0.107 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3208(_op_list_prepend)
518076 0.106 0.000 0.106 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:1200(_op_integer_neq_p)
1382777 0.105 0.000 0.105 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:485(_op_load_const)
135624 0.073 0.000 0.096 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:582(_op_make_closure)
1 0.000 0.000 0.084 0.084 /Users/dave/github/m6r/humbug/src/menai/menai_compiler.py:95(compile)
201468 0.060 0.000 0.075 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3779(_op_struct_get)
88278 0.053 0.000 0.057 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:691(_op_tail_call)
28776 0.034 0.000 0.048 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3721(_op_make_struct)
191180 0.040 0.000 0.040 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:2502(_op_string_eq_p)
554861 0.033 0.000 0.033 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:532(_op_jump)
76105 0.027 0.000 0.031 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:1298(_op_integer_add)
136285 0.028 0.000 0.028 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:603(_op_patch_closure)
57564 0.021 0.000 0.027 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3295(_op_list_length)
58202 0.023 0.000 0.025 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3234(_op_list_reverse)
2/1 0.000 0.000 0.025 0.025 /Users/dave/github/m6r/humbug/src/menai/menai_compiler.py:69(compile_to_resolved_ast)
2387/1 0.001 0.000 0.024 0.024 /Users/dave/github/m6r/humbug/src/menai/menai_ast_module_resolver.py:89(resolve)
3125/4 0.000 0.000 0.024 0.006 /Users/dave/github/m6r/humbug/src/menai/menai_ast_module_resolver.py:117(<genexpr>)
1 0.000 0.000 0.024 0.024 /Users/dave/github/m6r/humbug/src/menai/menai_ast_module_resolver.py:120(_resolve_import)
1 0.000 0.000 0.024 0.024 /Users/dave/github/m6r/humbug/src/menai/menai.py:1294(load_module)
1 0.000 0.000 0.016 0.016 /Users/dave/github/m6r/humbug/src/menai/menai_bytecode_builder.py:178(build)
33/1 0.002 0.000 0.015 0.015 /Users/dave/github/m6r/humbug/src/menai/menai_bytecode_builder.py:205(_emit_vcode)
201468 0.015 0.000 0.015 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_value.py:487(field_index)
32/28 0.000 0.000 0.015 0.001 /Users/dave/github/m6r/humbug/src/menai/menai_bytecode_builder.py:421(_emit_make_closure)
32/28 0.000 0.000 0.015 0.001 /Users/dave/github/m6r/humbug/src/menai/menai_bytecode_builder.py:450(_emit_lambda)
22968 0.011 0.000 0.014 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:2758(_op_string_ref)
163739 0.013 0.000 0.013 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:471(_op_load_empty_list)
163080 0.012 0.000 0.012 0.000 /Users/dave/github/m6r/humbug/src/menai/menai_vm.py:3741(<genexpr>)
...