Slow elaboration of `List Nat` literals
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- Dominant language
- Lean
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Description
Description
Long lists of natural number literals can take a long time to elaborate.
Context
Reported by @dwrensha on the Lean Zulip.
Steps to Reproduce
Given the following:
set_option trace.profiler true in
def dualEquationIds : List Nat :=
[ 1, 2, 3, 5, 4, 6, 7, 23, 28, 25, 31, 34, 24, 29, 30, 26, 32, 36, 27, 35,
33, 37, 8, 13, 10, 16, 19, 9, 14, 15, 11, 17, 21, 12, 20, 18, 22, 39, 38, 40,
41, 45, 43, 44, 42, 46, 255, 270, 260, 280, 290, 257, 273, 276, 263, 283, 298, 266, 294, 286,
302, 256, 271, 272, 261, 281, 292, 262, 291, 282, 293, 258, 274, 278, 264, 284, 300, 268, 295, 288,
305, 259, 277, 275, 279, 267, 287, 296, 304, 265, 299, 285, 301, 269, 303, 297, 289, 306, 203, 218,
208, 228, 238, 205, 221, 224, 211, 231, 246, 214, 242, 234, 250, 204, 219, 220, 209, 229, 240, 210,
239, 230, 241, 206, 222, 226, 212, 232, 248, 216, 243, 236, 253, 207, 225, 223, 227, 215, 235, 244,
252, 213, 247, 233, 249, 217, 251, 245, 237, 254, 151, 166, 156, 176, 186, 153, 169, 172, 159, 179,
194, 162, 190, 182, 198, 152, 167, 168, 157, 177, 188, 158, 187, 178, 189, 154, 170, 174, 160, 180,
196, 164, 191, 184, 201, 155, 173, 171, 175, 163, 183, 192, 200, 161, 195, 181, 197, 165, 199, 193,
185, 202, 99, 114, 104, 124, 134, 101, 117, 120, 107, 127, 142, 110, 138, 130, 146, 100, 115, 116,
105, 125, 136, 106, 135, 126, 137, 102, 118, 122, 108, 128, 144, 112, 139, 132, 149, 103, 121, 119,
123, 111, 131, 140, 148, 109, 143, 129, 145, 113, 147, 141, 133, 150, 47, 62, 52, 72, 82, 49,
65, 68, 55, 75, 90, 58, 86, 78, 94, 48, 63, 64, 53, 73, 84, 54, 83, 74, 85, 50,
66, 70, 56, 76, 92, 60, 87, 80, 97, 51, 69, 67, 71, 59, 79, 88, 96, 57, 91, 77,
93, 61, 95, 89, 81, 98, 359, 364, 361, 367, 370, 360, 365, 366, 362, 368, 372, 363, 371, 369,
373, 388, 378, 399, 385, 375, 395, 391, 381, 403, 407, 387, 377, 398, 384, 374, 394, 390, 380, 402,
406, 389, 379, 400, 401, 386, 376, 396, 397, 392, 382, 404, 409, 393, 383, 408, 405, 410, 307, 312,
309, 315, 318, 308, 313, 314, 310, 316, 320, 311, 319, 317, 321, 336, 326, 347, 333, 323, 343, 339,
329, 351, 355, 335, 325, 346, 332, 322, 342, 338, 328, 350, 354, 337, 327, 348, 349, 334, 324, 344,
345, 340, 330, 352, 357, 341, 331, 356, 353, 358,3050,3102,3065,3139,3176,3055,3112,3122,3075,3149,
3210,3085,3193,3159,3227,3052,3105,3108,3068,3142,3184,3071,3180,3145,3188,3058,3115,3130,3078,3152,
3218,3093,3197,3167,3242,3061,3126,3118,3134,3089,3163,3201,3237,3081,3214,3155,3222,3097,3232,3205,
3171,3247,3051,3103,3104,3066,3140,3178,3067,3177,3141,3179,3056,3113,3124,3076,3150,3212,3087,3194,
3161,3230,3057,3123,3114,3125,3086,3160,3195,3229,3077,3211,3151,3213,3088,3228,3196,3162,3231,3053,
3106,3110,3069,3143,3186,3073,3181,3147,3191,3059,3116,3132,3079,3153,3220,3095,3198,3169,3245,3063,
3127,3120,3137,3090,3164,3203,3239,3083,3215,3157,3225,3100,3233,3208,3174,3251,3054,3109,3107,3111,
3072,3146,3182,3190,3070,3185,3144,3187,3074,3189,3183,3148,3192,3062,3119,3128,3136,3082,3156,3216,
3224,3091,3202,3165,3240,3099,3206,3235,3173,3250,3060,3131,3117,3133,3094,3168,3199,3244,3080,3219,
3154,3221,3096,3243,3200,3170,3246,3064,3135,3129,3121,3138,3098,3172,3234,3207,3249,3092,3238,3166,
3204,3241,3084,3223,3217,3158,3226,3101,3248,3236,3209,3175,3252,2847,2899,2862,2936,2973,2852,2909,
2919,2872,2946,3007,2882,2990,2956,3024,2849,2902,2905,2865,2939,2981,2868,2977,2942,2985,2855,2912,
2927,2875,2949,3015,2890,2994,2964,3039,2858,2923,2915,2931,2886,2960,2998,3034,2878,3011,2952,3019,
2894,3029,3002,2968,3044,2848,2900,2901,2863,2937,2975,2864,2974,2938,2976,2853,2910,2921,2873,2947,
3009,2884,2991,2958,3027,2854,2920,2911,2922,2883,2957,2992,3026,2874,3008,2948,3010,2885,3025,2993,
2959,3028,2850,2903,2907,2866,2940,2983,2870,2978,2944,2988,2856,2913,2929,2876,2950,3017,2892,2995,
2966,3042,2860,2924,2917,2934,2887,2961,3000,3036,2880,3012,2954,3022,2897,3030,3005,2971,3048,2851,
2906,2904,2908,2869,2943,2979,2987,2867,2982,2941,2984,2871,2986,2980,2945,2989,2859,2916,2925,2933,
2879,2953,3013,3021,2888,2999,2962,3037,2896,3003,3032,2970,3047,2857,2928,2914,2930,2891,2965,2996,
3041,2877,3016,2951,3018,2893,3040,2997,2967,3043,2861,2932,2926,2918,2935,2895,2969,3031,3004,3046,
2889,3035,2963,3001,3038,2881,3020,3014,2955,3023,2898,3045,3033,3006,2972,3049,2644,2696,2659,2733,
2770,2649,2706,2716,2669,2743,2804,2679,2787,2753,2821,2646,2699,2702,2662,2736,2778,2665,2774,2739,
2782,2652,2709,2724,2672,2746,2812,2687,2791,2761,2836,2655,2720,2712,2728,2683,2757,2795,2831,2675,
2808,2749,2816,2691,2826,2799,2765,2841,2645,2697,2698,2660,2734,2772,2661,2771,2735,2773,2650,2707,
2718,2670,2744,2806,2681,2788,2755,2824,2651,2717,2708,2719,2680,2754,2789,2823,2671,2805,2745,2807,
2682,2822,2790,2756,2825,2647,2700,2704,2663,2737,2780,2667,2775,2741,2785,2653,2710,2726,2673,2747,
2814,2689,2792,2763,2839,2657,2721,2714,2731,2684,2758,2797,2833,2677,2809,2751,2819,2694,2827,2802,
2768,2845,2648,2703,2701,2705,2666,2740,2776,2784,2664,2779,2738,2781,2668,2783,2777,2742,2786,2656]
Expected behavior: Elaborates quickly
Actual behavior: Takes 1.4s to elaborate
Versions
4.13.0-rc3 macOS m2
Additional Information
Doubling the length of the list takes 4.6s, and quadrupling it takes 19.4s, suggesting there is some superlinear algorithm in elaboration (the amount of time in seconds taken to elaborate a list of length n is roughly modeled by (0.0012 * n) ^ 2).
Related issue: #5502
Impact
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Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the List Nat literal example from the issue with set_option trace.profiler true on Lean 4.13.0-rc3, then compare the reported timings for the original, doubled, and quadrupled lists. Use related issue #5502 as context; done means long List Nat literals elaborate quickly without the reported superlinear scaling.
Written by the indexing model from the issue text.
Assessment
- Domain
- compilers, performance
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Active
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100