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System F

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1685: 2995: 1307: 2687: 1680:{\displaystyle {\begin{aligned}\mathrm {AND} &=\lambda x^{\mathsf {Boolean}}\lambda y^{\mathsf {Boolean}}{.}x\,{\mathsf {Boolean}}\,y\,\mathbf {F} \\\mathrm {OR} &=\lambda x^{\mathsf {Boolean}}\lambda y^{\mathsf {Boolean}}{.}x\,{\mathsf {Boolean}}\,\mathbf {T} \,y\\\mathrm {NOT} &=\lambda x^{\mathsf {Boolean}}{.}x\,{\mathsf {Boolean}}\,\mathbf {F} \,\mathbf {T} \end{aligned}}} 2990:{\displaystyle {\begin{aligned}0&:=\Lambda \alpha .\lambda x^{\alpha }.\lambda f^{\alpha \to \alpha }.x\\1&:=\Lambda \alpha .\lambda x^{\alpha }.\lambda f^{\alpha \to \alpha }.fx\\2&:=\Lambda \alpha .\lambda x^{\alpha }.\lambda f^{\alpha \to \alpha }.f(fx)\\3&:=\Lambda \alpha .\lambda x^{\alpha }.\lambda f^{\alpha \to \alpha }.f(f(fx))\end{aligned}}} 2257: 2516: 519: 2086: 2619: 1996: 422: 3054: 1299: 168: 2383: 995: 924: 429: 2675: 2252:{\displaystyle \mathrm {ISZERO} =\lambda n^{\forall \alpha .(\alpha \rightarrow \alpha )\rightarrow \alpha \rightarrow \alpha }{.}n\,{\mathsf {Boolean}}\,(\lambda x^{\mathsf {Boolean}}{.}\mathbf {F} )\,\mathbf {T} } 2332: 3158:: that every term in F2 satisfies a logical relation, which can be embedded into the logical relations P2. Reynolds proved that a Girard projection followed by a Reynolds embedding form the identity, i.e., the 2531: 3450: 1126: 1043: 710: 1866: 3154:: that in second-order intuitionistic predicate logic (P2), functions from the natural numbers to the natural numbers that can be proved total, form a projection from P2 into F2. Reynolds proved the 2692: 2536: 1312: 335: 4018: 1004:— not two — arguments. The latter two should be lambda expressions, but the first one should be a type. This fact is reflected in the fact that the type of these expressions is 1176:); otherwise, if such functions could be named (within System F), then there would be no need for the lambda-expressive apparatus capable of defining functions anonymously and for the 599: 2045: 1858: 1812: 1730: 1085: 776: 669: 3284: 778:
is the type of all functions which take as input a type α and two expressions of type α, and produce as output an expression of type α (note that we consider
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family. Over time, as the restrictions of HM-style type systems have become apparent, languages have steadily moved to more expressive logics for their type systems.
730: 619: 571: 279: 255: 191: 3256: 2511:{\displaystyle \forall \alpha .(K_{1}^{1}\rightarrow \dots \rightarrow \alpha )\dots \rightarrow (K_{1}^{m}\rightarrow \dots \rightarrow \alpha )\rightarrow \alpha } 104: 3234: 2367: 796: 1770: 1750: 930: 859: 3922:(1971). "Une Extension de l'Interpretation de Gödel à l'Analyse, et son Application à l'Élimination des Coupures dans l'Analyse et la Théorie des Types". 514:{\displaystyle {\frac {\Gamma ,\alpha ~{\text{type}}\vdash M{\mathbin {:}}\sigma }{\Gamma \vdash \Lambda \alpha .M{\mathbin {:}}\forall \alpha .\sigma }}} 3956: 3088:
The version of System F used in this article is as an explicitly typed, or Church-style, calculus. The typing information contained in λ-terms makes
4110: 3743: 289: 2627: 3150:, the second-order polymorphic lambda calculus (F2) was discovered by Girard (1972) and independently by Reynolds (1974). Girard proved the 3980: 3894: 2614:{\displaystyle {\begin{aligned}{\mathit {zero}}&:\mathrm {N} \\{\mathit {succ}}&:\mathrm {N} \rightarrow \mathrm {N} \end{aligned}}} 2285: 1045:; the universal quantifier binding the α corresponds to the Λ binding the alpha in the lambda expression itself. Also, note that 3664: 3397: 4067: 4045: 4011: 1991:{\displaystyle \mathrm {IFTHENELSE} =\Lambda \alpha .\lambda x^{\mathsf {Boolean}}\lambda y^{\alpha }\lambda z^{\alpha }.x\alpha yz} 1090: 1007: 674: 3130:, a Haskell compiler, goes beyond HM (as of 2008) and uses System F extended with non-syntactic type equality; non-HM features in 3572: 3135: 3115: 3848: 3119: 58: 2268: 417:{\displaystyle {\frac {\Gamma \vdash M{\mathbin {:}}\forall \alpha .\sigma }{\Gamma \vdash M\tau {\mathbin {:}}\sigma }}} 297: 3990:
Wells, J. B. (1994). "Typability and type checking in the second-order lambda-calculus are equivalent and undecidable".
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Cardelli, Luca; Martini, Simone; Mitchell, John C.; Scedrov, Andre (1994). "An extension of system F with subtyping".
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However, in it was shown that the obvious rules of conversion for this system, called F by chance, were converging.
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is the system which allows functions from types to types where the argument (and result) may be of any order.
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The typing rules of System F are those of simply typed lambda calculus with the addition of the following:
3902: 1177: 3747: 2008: 1821: 1775: 1693: 1048: 739: 632: 90:, and binders for them. As an example, the fact that the identity function can have any type of the form 86:
has variables ranging over terms, and binders for them, System F additionally has variables ranging over
3073: 1173: 285: 38: 4061: 4105: 3147: 301: 54: 3263: 530: 3761: 3289: 3108: 3049:{\displaystyle \forall \alpha .(\alpha \rightarrow \alpha )\rightarrow \alpha \rightarrow \alpha } 2054: 1153: 1131: 830: 808: 3744:"The Church Project: Typability and type checking in {S}ystem {F} are equivalent and undecidable" 3367: 3203: 1294:{\displaystyle {\mathsf {Boolean}}\rightarrow {\mathsf {Boolean}}\rightarrow {\mathsf {Boolean}}} 73: 3328: 3093: 2267:
System F allows recursive constructions to be embedded in a natural manner, related to that in
163:{\displaystyle \vdash \Lambda \alpha .\lambda x^{\alpha }.x:\forall \alpha .\alpha \to \alpha } 4041: 4033: 4007: 3976: 3890: 3603: 3525: 3505: 3485: 1186: 799: 220: 200: 715: 604: 556: 264: 240: 176: 3999: 3952: 3944:
Interprétation fonctionnelle et élimination des coupures de l'arithmétique d'ordre supérieur
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for a Curry-style variant of System F, that is, one that lacks explicit typing annotations.
3097: 76: 69: 3212: 2345: 3841: 3479: 3174: 2074: 850: 781: 309: 990:{\displaystyle \mathbf {F} =\Lambda \alpha {.}\lambda x^{\alpha }\lambda y^{\alpha }{.}y} 919:{\displaystyle \mathbf {T} =\Lambda \alpha {.}\lambda x^{\alpha }\lambda y^{\alpha }{.}x} 3358:(the kind of functions from types to types, where the argument type is of a lower order) 621:
is bound. The first rule is that of application, and the second is that of abstraction.
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of the arguments for these mappings: they must be types rather than values. System F
3192: 3089: 733: 281:; the expression after the colon is the type of the lambda expression preceding it.) 194: 20: 3202:
can be defined inductively on a family of systems, where induction is based on the
3111:", or simply "HM", does have an easy type inference algorithm and is used for many 1128:, but it is not a symbol of System F itself, but rather a "meta-symbol". Likewise, 217:
is traditionally used to denote type-level functions, as opposed to the lower-case
4034:"V Polymorphism Ch. 23. Universal Types, Ch. 25. An ML Implementation of System F" 3634:
Girard, Jean-Yves (1986). "The system F of variable types, fifteen years later".
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are also "meta-symbols", convenient shorthands, of System F "assemblies" (in the
3614: 3177: 308:, together with even more expressive typed lambda calculi, including those with 305: 3096:(1994) settled an "embarrassing open problem" by proving that type checking is 4003: 3668: 304:
that uses only universal quantification. System F can be seen as part of the
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For instance, the natural numbers can be defined as an inductive datatype
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in System F (without explicit type annotations) is undecidable. Under the
3785: 3720:"Typability and type checking in System F are equivalent and undecidable" 3609: 66: 2327:{\displaystyle K_{1}\rightarrow K_{2}\rightarrow \dots \rightarrow S} 3131: 1860:-typed terms as decision functions. However, if one is requested: 3669:"Practical Foundations for Programming Languages, Second Edition" 3993: 3445:{\displaystyle F_{\omega }={\underset {1\leq i}{\bigcup }}F_{i}} 3107:
for System F is impossible. A restriction of System F known as "
3606:— the existentially quantified counterparts of universal types 1203:-terms, we can define some logic operators (which are of type 3191:
combines the first axis (polymorphism) with the second axis (
1752:, specifying that the other two parameters that are given to 1121:{\displaystyle \forall \alpha .\alpha \to \alpha \to \alpha } 1038:{\displaystyle \forall \alpha .\alpha \to \alpha \to \alpha } 705:{\displaystyle \forall \alpha .\alpha \to \alpha \to \alpha } 2582: 2579: 2576: 2573: 2550: 2547: 2544: 2541: 237:
which is used for value-level functions. (The superscripted
2677:. The terms of this type comprise a typed version of the 3482:), though it does permit mappings from values to values ( 3470:
of the arguments in these mappings, it does restrict the
57:, thus forming a theoretical basis for languages such as 3559:, pronounced "F-sub", is an extension of system F with 300:, System F corresponds to the fragment of second-order 3969:
Girard, Jean-Yves; Lafont, Yves; Taylor, Paul (1989).
3924:
Proceedings of the Second Scandinavian Logic Symposium
3687:"Proofs of Programs and Formalisation of Mathematics" 3528: 3508: 3488: 3400: 3370: 3331: 3292: 3266: 3244: 3215: 3009: 2690: 2630: 2624:
The System F type corresponding to this structure is
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The following two definitions for the boolean values
784: 742: 718: 677: 635: 607: 579: 559: 533: 432: 338: 267: 243: 223: 203: 179: 107: 3849:Programming Languages and Foundations at Edinburgh 3534: 3514: 3494: 3444: 3383: 3350: 3317: 3278: 3250: 3228: 3048: 3000:If we reverse the order of the curried arguments ( 2989: 2669: 2613: 2510: 2373:of these constructors, you can define the type of 2361: 2326: 2251: 2065: 2039: 1990: 1852: 1814:. As in Church encodings, there is no need for an 1806: 1764: 1744: 1724: 1679: 1293: 1195: 1164: 1142: 1120: 1079: 1037: 989: 918: 841: 819: 790: 770: 724: 704: 663: 613: 593: 565: 545: 513: 416: 273: 249: 229: 209: 185: 162: 98:would be formalized in System F as the judgement 3842:The Girard-Reynolds Isomorphism (second edition) 3522:abstraction), and mappings from types to types ( 3173:While System F corresponds to the first axis of 3080:, and returns another single-argument function. 2047:-typed value. The most fundamental predicate is 3762:"System FC: equality constraints and coercions" 3478:does not permit mappings from values to types ( 329: 3946:(Ph.D. thesis) (in French), UniversitĂ© Paris 7 3996:Symposium on Logic in Computer Science (LICS) 3502:abstraction), mappings from types to values ( 8: 19:For the electronic trance music artist, see 3864:. North Holland, Amsterdam. pp. 4–56. 3195:); it is a different, more complex system. 1000:(Note that the above two functions require 3869: 3735: 3527: 3507: 3487: 3436: 3414: 3405: 3399: 3375: 3369: 3342: 3330: 3303: 3291: 3265: 3243: 3220: 3214: 3008: 2944: 2928: 2868: 2852: 2801: 2785: 2737: 2721: 2691: 2689: 2629: 2602: 2594: 2572: 2571: 2562: 2540: 2539: 2535: 2533: 2476: 2464: 2459: 2420: 2408: 2403: 2385: 2353: 2347: 2306: 2293: 2287: 2244: 2243: 2235: 2230: 2205: 2204: 2193: 2169: 2168: 2167: 2159: 2120: 2090: 2088: 2058: 2056: 2013: 2012: 2010: 1967: 1954: 1922: 1921: 1870: 1868: 1826: 1825: 1823: 1780: 1779: 1777: 1757: 1737: 1698: 1697: 1695: 1668: 1667: 1662: 1661: 1637: 1636: 1635: 1627: 1602: 1601: 1576: 1568: 1563: 1562: 1538: 1537: 1536: 1528: 1503: 1502: 1470: 1469: 1447: 1438: 1437: 1433: 1409: 1408: 1407: 1399: 1374: 1373: 1341: 1340: 1315: 1311: 1309: 1267: 1266: 1239: 1238: 1211: 1210: 1208: 1188: 1157: 1155: 1135: 1133: 1092: 1053: 1052: 1050: 1009: 979: 973: 960: 948: 934: 932: 908: 902: 889: 877: 863: 861: 834: 832: 812: 810: 783: 744: 743: 741: 717: 676: 637: 636: 634: 606: 586: 578: 558: 532: 490: 489: 460: 459: 448: 433: 431: 400: 385: 384: 352: 351: 339: 337: 266: 242: 222: 202: 178: 127: 106: 4040:. MIT Press. pp. 339–362, 381–388. 3189:higher-order polymorphic lambda calculus 3072:. That is to say, a Church numeral is a 1180:, which works around that restriction.) 3626: 2342:itself appears within one of the types 3076:– it takes a single-argument function 2224: 2221: 2218: 2215: 2212: 2209: 2206: 2188: 2185: 2182: 2179: 2176: 2173: 2170: 2032: 2029: 2026: 2023: 2020: 2017: 2014: 1941: 1938: 1935: 1932: 1929: 1926: 1923: 1845: 1842: 1839: 1836: 1833: 1830: 1827: 1799: 1796: 1793: 1790: 1787: 1784: 1781: 1717: 1714: 1711: 1708: 1705: 1702: 1699: 1656: 1653: 1650: 1647: 1644: 1641: 1638: 1621: 1618: 1615: 1612: 1609: 1606: 1603: 1557: 1554: 1551: 1548: 1545: 1542: 1539: 1522: 1519: 1516: 1513: 1510: 1507: 1504: 1489: 1486: 1483: 1480: 1477: 1474: 1471: 1428: 1425: 1422: 1419: 1416: 1413: 1410: 1393: 1390: 1387: 1384: 1381: 1378: 1375: 1360: 1357: 1354: 1351: 1348: 1345: 1342: 1286: 1283: 1280: 1277: 1274: 1271: 1268: 1258: 1255: 1252: 1249: 1246: 1243: 1240: 1230: 1227: 1224: 1221: 1218: 1215: 1212: 1072: 1069: 1066: 1063: 1060: 1057: 1054: 849:are used, extending the definition of 763: 760: 757: 754: 751: 748: 745: 656: 653: 650: 647: 644: 641: 638: 3833: 3831: 3829: 3827: 3587:subtyping, which can be expressed in 594:{\displaystyle \alpha ~{\text{type}}} 65:. It was discovered independently by 7: 3571:since the 1980s because the core of 3542:abstraction at the level of types). 3060:is a function that takes a function 1690:Note that in the definitions above, 4072:: the workhorse of modern compilers 3862:Information and Computation, vol. 9 3746:. 29 September 2007. Archived from 3364:In the limit, we can define system 2073:if and only if its argument is the 2040:{\displaystyle {\mathsf {Boolean}}} 1853:{\displaystyle {\mathsf {Boolean}}} 1807:{\displaystyle {\mathsf {Boolean}}} 1725:{\displaystyle {\mathsf {Boolean}}} 1080:{\displaystyle {\mathsf {Boolean}}} 771:{\displaystyle {\mathsf {Boolean}}} 664:{\displaystyle {\mathsf {Boolean}}} 3958:Towards a Theory of Type Structure 3567:has been of central importance to 3509: 3010: 2912: 2836: 2769: 2705: 2631: 2603: 2595: 2563: 2387: 2121: 2106: 2103: 2100: 2097: 2094: 2091: 1905: 1898: 1895: 1892: 1889: 1886: 1883: 1880: 1877: 1874: 1871: 1583: 1580: 1577: 1451: 1448: 1322: 1319: 1316: 1094: 1011: 942: 871: 678: 496: 477: 471: 436: 372: 358: 342: 204: 142: 111: 14: 3685:Geuvers H, Nordström B, Dowek G. 1818:function as one can just use raw 3705:"Joe Wells's Research Interests" 3573:functional programming languages 3116:functional programming languages 2279:. These are functions typed as: 2245: 2236: 2059: 1669: 1663: 1564: 1439: 1158: 1136: 935: 864: 835: 813: 315:According to Girard, the "F" in 49:over types. System F formalizes 4111:Polymorphism (computer science) 4038:Types and Programming Languages 3887:Types and Programming Languages 3142:The Girard-Reynolds Isomorphism 3056:), then the Church numeral for 2338:Recursivity is manifested when 3992:Proceedings of the 9th Annual 3975:. Cambridge University Press. 3466:places no restrictions on the 3279:{\displaystyle J\Rightarrow K} 3270: 3040: 3034: 3031: 3025: 3019: 2980: 2977: 2968: 2962: 2948: 2895: 2886: 2872: 2805: 2741: 2681:, the first few of which are: 2661: 2658: 2652: 2646: 2643: 2599: 2502: 2499: 2493: 2487: 2484: 2470: 2452: 2449: 2443: 2437: 2431: 2428: 2414: 2396: 2318: 2312: 2299: 2240: 2194: 2151: 2145: 2142: 2136: 2130: 2005:is a function which returns a 1263: 1235: 1112: 1106: 1087:is a convenient shorthand for 1029: 1023: 785: 696: 690: 601:in the context indicates that 408: 394: 154: 1: 3932:10.1016/S0049-237X(08)70843-7 3926:. Amsterdam. pp. 63–92. 3811:"OCaml 4.09 reference manual" 3737:10.1016/S0168-0072(98)00047-5 546:{\displaystyle \sigma ,\tau } 3786:"OCaml 4.00.1 release notes" 3648:10.1016/0304-3975(86)90044-7 3636:Theoretical Computer Science 3318:{\displaystyle J\in F_{n-1}} 3103:Wells's result implies that 3084:Use in programming languages 3064:as argument and returns the 2066:{\displaystyle \mathbf {T} } 1165:{\displaystyle \mathbf {F} } 1143:{\displaystyle \mathbf {T} } 842:{\displaystyle \mathbf {F} } 820:{\displaystyle \mathbf {T} } 426: 332: 84:simply typed lambda calculus 43:simply typed lambda calculus 35:second-order lambda calculus 3569:programming language theory 3384:{\displaystyle F_{\omega }} 3160:Girard-Reynolds Isomorphism 31:polymorphic lambda calculus 4132: 3703:Wells, J.B. (2005-01-20). 3351:{\displaystyle K\in F_{n}} 3206:permitted in each system: 18: 4032:Pierce, Benjamin (2002). 3885:Pierce, Benjamin (2002). 3707:. Heriot-Watt University. 4004:10.1109/LICS.1994.316068 3535:{\displaystyle \lambda } 3515:{\displaystyle \Lambda } 3495:{\displaystyle \lambda } 2269:Martin-Löf's type theory 1196:{\displaystyle \lambda } 573:is a type variable, and 298:Curry–Howard isomorphism 230:{\displaystyle \lambda } 210:{\displaystyle \Lambda } 47:universal quantification 3845:University of Edinburgh 3581:parametric polymorphism 3258:(the kind of types) and 3134:'s type system include 2271:. Abstract structures ( 725:{\displaystyle \alpha } 614:{\displaystyle \alpha } 566:{\displaystyle \alpha } 274:{\displaystyle \alpha } 250:{\displaystyle \alpha } 186:{\displaystyle \alpha } 51:parametric polymorphism 3903:Bounded quantification 3871:10.1006/inco.1994.1013 3536: 3516: 3496: 3446: 3385: 3352: 3319: 3280: 3252: 3251:{\displaystyle \star } 3230: 3152:Representation Theorem 3050: 2991: 2671: 2615: 2512: 2363: 2328: 2253: 2067: 2041: 1992: 1854: 1808: 1766: 1746: 1732:is a type argument to 1726: 1681: 1295: 1197: 1178:fixed-point combinator 1166: 1144: 1122: 1081: 1039: 991: 920: 843: 821: 792: 772: 726: 706: 665: 615: 595: 567: 547: 515: 418: 319:was picked by chance. 275: 251: 231: 211: 187: 164: 3750:on 29 September 2007. 3724:Ann. Pure Appl. Logic 3579:family, support both 3537: 3517: 3497: 3447: 3386: 3353: 3320: 3281: 3253: 3231: 3229:{\displaystyle F_{n}} 3074:higher-order function 3051: 2992: 2672: 2616: 2513: 2364: 2362:{\displaystyle K_{i}} 2329: 2254: 2068: 2042: 1993: 1855: 1809: 1767: 1747: 1727: 1682: 1296: 1198: 1183:Then, with these two 1167: 1145: 1123: 1082: 1040: 992: 921: 844: 822: 793: 773: 727: 707: 666: 616: 596: 568: 548: 516: 419: 286:term rewriting system 276: 257:means that the bound 252: 232: 212: 188: 165: 55:programming languages 39:typed lambda calculus 16:Typed lambda calculus 3998:. pp. 176–185. 3718:Wells, J.B. (1999). 3575:, like those in the 3526: 3506: 3486: 3462:Note that although F 3398: 3368: 3329: 3290: 3264: 3242: 3213: 3148:intuitionistic logic 3007: 2688: 2628: 2532: 2384: 2346: 2286: 2275:) are created using 2087: 2055: 2009: 1867: 1822: 1776: 1756: 1736: 1694: 1308: 1207: 1187: 1154: 1132: 1091: 1049: 1008: 931: 860: 831: 809: 791:{\displaystyle \to } 782: 740: 716: 675: 671:type is defined as: 633: 625:Logic and predicates 605: 577: 557: 531: 430: 336: 302:intuitionistic logic 290:strongly normalizing 265: 241: 221: 201: 177: 105: 41:that introduces, to 4062:Summary of System F 3156:Abstraction Theorem 2469: 2413: 2263:System F structures 4019:Postscript version 3766:gitlab.haskell.org 3532: 3512: 3492: 3442: 3430: 3381: 3348: 3315: 3276: 3248: 3226: 3092:straightforward. 3046: 2987: 2985: 2667: 2611: 2609: 2525:with constructors 2508: 2455: 2399: 2359: 2324: 2249: 2063: 2037: 1988: 1850: 1804: 1762: 1742: 1722: 1677: 1675: 1291: 1193: 1162: 1140: 1118: 1077: 1035: 987: 916: 839: 817: 788: 768: 722: 702: 661: 611: 591: 563: 543: 511: 414: 271: 247: 227: 207: 197:. The upper-case 183: 160: 74:computer scientist 4096:1974 in computing 4091:1971 in computing 4064:by Franck Binard. 3982:978-0-521-37181-0 3940:Girard, Jean-Yves 3920:Girard, Jean-Yves 3896:978-0-262-16209-8 3674:. pp. 142–3. 3604:Existential types 3415: 1765:{\displaystyle x} 1745:{\displaystyle x} 800:right-associative 589: 585: 525: 524: 509: 451: 447: 412: 45:, a mechanism of 4123: 4051: 4017: 3986: 3972:Proofs and Types 3965: 3963: 3947: 3935: 3905: 3900: 3882: 3876: 3875: 3873: 3857: 3851: 3835: 3822: 3821: 3819: 3818: 3807: 3801: 3800: 3798: 3797: 3782: 3776: 3775: 3773: 3772: 3758: 3752: 3751: 3741: 3739: 3730:(1–3): 111–156. 3715: 3709: 3708: 3700: 3694: 3693: 3691: 3682: 3676: 3675: 3673: 3661: 3655: 3654: 3631: 3541: 3539: 3538: 3533: 3521: 3519: 3518: 3513: 3501: 3499: 3498: 3493: 3451: 3449: 3448: 3443: 3441: 3440: 3431: 3429: 3410: 3409: 3390: 3388: 3387: 3382: 3380: 3379: 3357: 3355: 3354: 3349: 3347: 3346: 3324: 3322: 3321: 3316: 3314: 3313: 3285: 3283: 3282: 3277: 3257: 3255: 3254: 3249: 3235: 3233: 3232: 3227: 3225: 3224: 3146:In second-order 3113:statically typed 3079: 3071: 3067: 3063: 3059: 3055: 3053: 3052: 3047: 2996: 2994: 2993: 2988: 2986: 2955: 2954: 2933: 2932: 2879: 2878: 2857: 2856: 2812: 2811: 2790: 2789: 2748: 2747: 2726: 2725: 2676: 2674: 2673: 2668: 2620: 2618: 2617: 2612: 2610: 2606: 2598: 2586: 2585: 2566: 2554: 2553: 2524: 2517: 2515: 2514: 2509: 2480: 2468: 2463: 2424: 2412: 2407: 2376: 2372: 2368: 2366: 2365: 2360: 2358: 2357: 2341: 2333: 2331: 2330: 2325: 2311: 2310: 2298: 2297: 2274: 2258: 2256: 2255: 2250: 2248: 2239: 2234: 2229: 2228: 2227: 2192: 2191: 2163: 2158: 2157: 2109: 2079: 2072: 2070: 2069: 2064: 2062: 2050: 2046: 2044: 2043: 2038: 2036: 2035: 1997: 1995: 1994: 1989: 1972: 1971: 1959: 1958: 1946: 1945: 1944: 1901: 1859: 1857: 1856: 1851: 1849: 1848: 1817: 1813: 1811: 1810: 1805: 1803: 1802: 1771: 1769: 1768: 1763: 1751: 1749: 1748: 1743: 1731: 1729: 1728: 1723: 1721: 1720: 1686: 1684: 1683: 1678: 1676: 1672: 1666: 1660: 1659: 1631: 1626: 1625: 1624: 1586: 1567: 1561: 1560: 1532: 1527: 1526: 1525: 1494: 1493: 1492: 1454: 1442: 1432: 1431: 1403: 1398: 1397: 1396: 1365: 1364: 1363: 1325: 1300: 1298: 1297: 1292: 1290: 1289: 1262: 1261: 1234: 1233: 1202: 1200: 1199: 1194: 1171: 1169: 1168: 1163: 1161: 1149: 1147: 1146: 1141: 1139: 1127: 1125: 1124: 1119: 1086: 1084: 1083: 1078: 1076: 1075: 1044: 1042: 1041: 1036: 996: 994: 993: 988: 983: 978: 977: 965: 964: 952: 938: 925: 923: 922: 917: 912: 907: 906: 894: 893: 881: 867: 848: 846: 845: 840: 838: 826: 824: 823: 818: 816: 797: 795: 794: 789: 777: 775: 774: 769: 767: 766: 731: 729: 728: 723: 711: 709: 708: 703: 670: 668: 667: 662: 660: 659: 620: 618: 617: 612: 600: 598: 597: 592: 590: 587: 583: 572: 570: 569: 564: 552: 550: 549: 544: 520: 518: 517: 512: 510: 508: 495: 494: 469: 465: 464: 452: 449: 445: 434: 423: 421: 420: 415: 413: 411: 404: 390: 389: 370: 357: 356: 340: 330: 280: 278: 277: 272: 256: 254: 253: 248: 236: 234: 233: 228: 216: 214: 213: 208: 192: 190: 189: 184: 169: 167: 166: 161: 132: 131: 77:John C. Reynolds 70:Jean-Yves Girard 4131: 4130: 4126: 4125: 4124: 4122: 4121: 4120: 4101:Lambda calculus 4081: 4080: 4071: 4058: 4048: 4031: 4028: 4026:Further reading 4023: 4014: 3989: 3983: 3968: 3961: 3951: 3938: 3918: 3914: 3909: 3908: 3897: 3884: 3883: 3879: 3859: 3858: 3854: 3836: 3825: 3816: 3814: 3809: 3808: 3804: 3795: 3793: 3784: 3783: 3779: 3770: 3768: 3760: 3759: 3755: 3742: 3717: 3716: 3712: 3702: 3701: 3697: 3689: 3684: 3683: 3679: 3671: 3663: 3662: 3658: 3633: 3632: 3628: 3623: 3600: 3592: 3566: 3557: 3551: 3549: 3524: 3523: 3504: 3503: 3484: 3483: 3480:dependent types 3477: 3465: 3458: 3432: 3419: 3401: 3396: 3395: 3371: 3366: 3365: 3338: 3327: 3326: 3299: 3288: 3287: 3262: 3261: 3240: 3239: 3236:permits kinds: 3216: 3211: 3210: 3201: 3185: 3171: 3169: 3144: 3086: 3077: 3069: 3065: 3061: 3057: 3005: 3004: 2984: 2983: 2940: 2924: 2905: 2899: 2898: 2864: 2848: 2829: 2823: 2822: 2797: 2781: 2762: 2756: 2755: 2733: 2717: 2698: 2686: 2685: 2679:Church numerals 2626: 2625: 2608: 2607: 2587: 2568: 2567: 2555: 2530: 2529: 2522: 2382: 2381: 2374: 2370: 2349: 2344: 2343: 2339: 2302: 2289: 2284: 2283: 2272: 2265: 2200: 2116: 2085: 2084: 2077: 2053: 2052: 2048: 2007: 2006: 1963: 1950: 1917: 1865: 1864: 1820: 1819: 1815: 1774: 1773: 1754: 1753: 1734: 1733: 1692: 1691: 1674: 1673: 1597: 1587: 1573: 1572: 1498: 1465: 1455: 1444: 1443: 1369: 1336: 1326: 1306: 1305: 1205: 1204: 1185: 1184: 1152: 1151: 1130: 1129: 1089: 1088: 1047: 1046: 1006: 1005: 969: 956: 929: 928: 898: 885: 858: 857: 851:Church booleans 829: 828: 807: 806: 780: 779: 738: 737: 714: 713: 673: 672: 631: 630: 627: 603: 602: 575: 574: 555: 554: 529: 528: 470: 435: 428: 427: 371: 341: 334: 333: 325: 310:dependent types 263: 262: 239: 238: 219: 218: 199: 198: 175: 174: 123: 103: 102: 24: 17: 12: 11: 5: 4129: 4127: 4119: 4118: 4113: 4108: 4103: 4098: 4093: 4083: 4082: 4079: 4078: 4076:Greg Morrisett 4069: 4065: 4057: 4056:External links 4054: 4053: 4052: 4046: 4027: 4024: 4022: 4021: 4012: 3987: 3981: 3966: 3953:Reynolds, John 3949: 3936: 3915: 3913: 3910: 3907: 3906: 3901:, Chapter 26: 3895: 3877: 3852: 3823: 3802: 3777: 3753: 3710: 3695: 3677: 3656: 3625: 3624: 3622: 3619: 3618: 3617: 3612: 3607: 3599: 3596: 3590: 3564: 3555: 3550: 3547: 3544: 3531: 3511: 3491: 3475: 3463: 3456: 3453: 3452: 3439: 3435: 3428: 3425: 3422: 3418: 3413: 3408: 3404: 3378: 3374: 3362: 3361: 3360: 3359: 3345: 3341: 3337: 3334: 3312: 3309: 3306: 3302: 3298: 3295: 3275: 3272: 3269: 3259: 3247: 3223: 3219: 3199: 3193:type operators 3183: 3170: 3167: 3164: 3143: 3140: 3109:Hindley–Milner 3105:type inference 3085: 3082: 3045: 3042: 3039: 3036: 3033: 3030: 3027: 3024: 3021: 3018: 3015: 3012: 2998: 2997: 2982: 2979: 2976: 2973: 2970: 2967: 2964: 2961: 2958: 2953: 2950: 2947: 2943: 2939: 2936: 2931: 2927: 2923: 2920: 2917: 2914: 2911: 2908: 2906: 2904: 2901: 2900: 2897: 2894: 2891: 2888: 2885: 2882: 2877: 2874: 2871: 2867: 2863: 2860: 2855: 2851: 2847: 2844: 2841: 2838: 2835: 2832: 2830: 2828: 2825: 2824: 2821: 2818: 2815: 2810: 2807: 2804: 2800: 2796: 2793: 2788: 2784: 2780: 2777: 2774: 2771: 2768: 2765: 2763: 2761: 2758: 2757: 2754: 2751: 2746: 2743: 2740: 2736: 2732: 2729: 2724: 2720: 2716: 2713: 2710: 2707: 2704: 2701: 2699: 2697: 2694: 2693: 2666: 2663: 2660: 2657: 2654: 2651: 2648: 2645: 2642: 2639: 2636: 2633: 2622: 2621: 2605: 2601: 2597: 2593: 2590: 2588: 2584: 2581: 2578: 2575: 2570: 2569: 2565: 2561: 2558: 2556: 2552: 2549: 2546: 2543: 2538: 2537: 2519: 2518: 2507: 2504: 2501: 2498: 2495: 2492: 2489: 2486: 2483: 2479: 2475: 2472: 2467: 2462: 2458: 2454: 2451: 2448: 2445: 2442: 2439: 2436: 2433: 2430: 2427: 2423: 2419: 2416: 2411: 2406: 2402: 2398: 2395: 2392: 2389: 2369:. If you have 2356: 2352: 2336: 2335: 2323: 2320: 2317: 2314: 2309: 2305: 2301: 2296: 2292: 2264: 2261: 2260: 2259: 2247: 2242: 2238: 2233: 2226: 2223: 2220: 2217: 2214: 2211: 2208: 2203: 2199: 2196: 2190: 2187: 2184: 2181: 2178: 2175: 2172: 2166: 2162: 2156: 2153: 2150: 2147: 2144: 2141: 2138: 2135: 2132: 2129: 2126: 2123: 2119: 2115: 2112: 2108: 2105: 2102: 2099: 2096: 2093: 2075:Church numeral 2061: 2051:which returns 2034: 2031: 2028: 2025: 2022: 2019: 2016: 1999: 1998: 1987: 1984: 1981: 1978: 1975: 1970: 1966: 1962: 1957: 1953: 1949: 1943: 1940: 1937: 1934: 1931: 1928: 1925: 1920: 1916: 1913: 1910: 1907: 1904: 1900: 1897: 1894: 1891: 1888: 1885: 1882: 1879: 1876: 1873: 1847: 1844: 1841: 1838: 1835: 1832: 1829: 1801: 1798: 1795: 1792: 1789: 1786: 1783: 1761: 1741: 1719: 1716: 1713: 1710: 1707: 1704: 1701: 1688: 1687: 1671: 1665: 1658: 1655: 1652: 1649: 1646: 1643: 1640: 1634: 1630: 1623: 1620: 1617: 1614: 1611: 1608: 1605: 1600: 1596: 1593: 1590: 1588: 1585: 1582: 1579: 1575: 1574: 1571: 1566: 1559: 1556: 1553: 1550: 1547: 1544: 1541: 1535: 1531: 1524: 1521: 1518: 1515: 1512: 1509: 1506: 1501: 1497: 1491: 1488: 1485: 1482: 1479: 1476: 1473: 1468: 1464: 1461: 1458: 1456: 1453: 1450: 1446: 1445: 1441: 1436: 1430: 1427: 1424: 1421: 1418: 1415: 1412: 1406: 1402: 1395: 1392: 1389: 1386: 1383: 1380: 1377: 1372: 1368: 1362: 1359: 1356: 1353: 1350: 1347: 1344: 1339: 1335: 1332: 1329: 1327: 1324: 1321: 1318: 1314: 1313: 1288: 1285: 1282: 1279: 1276: 1273: 1270: 1265: 1260: 1257: 1254: 1251: 1248: 1245: 1242: 1237: 1232: 1229: 1226: 1223: 1220: 1217: 1214: 1192: 1174:Bourbaki sense 1160: 1138: 1117: 1114: 1111: 1108: 1105: 1102: 1099: 1096: 1074: 1071: 1068: 1065: 1062: 1059: 1056: 1034: 1031: 1028: 1025: 1022: 1019: 1016: 1013: 998: 997: 986: 982: 976: 972: 968: 963: 959: 955: 951: 947: 944: 941: 937: 926: 915: 911: 905: 901: 897: 892: 888: 884: 880: 876: 873: 870: 866: 837: 815: 787: 765: 762: 759: 756: 753: 750: 747: 736:. This means: 721: 701: 698: 695: 692: 689: 686: 683: 680: 658: 655: 652: 649: 646: 643: 640: 626: 623: 610: 582: 562: 542: 539: 536: 523: 522: 507: 504: 501: 498: 493: 488: 485: 482: 479: 476: 473: 468: 463: 458: 455: 444: 441: 438: 425: 410: 407: 403: 399: 396: 393: 388: 383: 380: 377: 374: 369: 366: 363: 360: 355: 350: 347: 344: 324: 321: 294:type inference 288:, System F is 270: 246: 226: 206: 182: 171: 170: 159: 156: 153: 150: 147: 144: 141: 138: 135: 130: 126: 122: 119: 116: 113: 110: 15: 13: 10: 9: 6: 4: 3: 2: 4128: 4117: 4114: 4112: 4109: 4107: 4104: 4102: 4099: 4097: 4094: 4092: 4089: 4088: 4086: 4077: 4073: 4066: 4063: 4060: 4059: 4055: 4049: 4047:0-262-16209-1 4043: 4039: 4035: 4030: 4029: 4025: 4020: 4015: 4013:0-8186-6310-3 4009: 4005: 4001: 3997: 3995: 3988: 3984: 3978: 3974: 3973: 3967: 3960: 3959: 3954: 3950: 3945: 3941: 3937: 3933: 3929: 3925: 3921: 3917: 3916: 3911: 3904: 3898: 3892: 3889:. MIT Press. 3888: 3881: 3878: 3872: 3867: 3863: 3856: 3853: 3850: 3846: 3843: 3839: 3838:Philip Wadler 3834: 3832: 3830: 3828: 3824: 3812: 3806: 3803: 3791: 3787: 3781: 3778: 3767: 3763: 3757: 3754: 3749: 3745: 3738: 3733: 3729: 3725: 3721: 3714: 3711: 3706: 3699: 3696: 3692:. p. 51. 3688: 3681: 3678: 3670: 3666: 3660: 3657: 3653: 3649: 3645: 3641: 3637: 3630: 3627: 3620: 3616: 3613: 3611: 3608: 3605: 3602: 3601: 3597: 3595: 3593: 3586: 3582: 3578: 3574: 3570: 3562: 3558: 3545: 3543: 3529: 3489: 3481: 3473: 3469: 3460: 3437: 3433: 3426: 3423: 3420: 3416: 3411: 3406: 3402: 3394: 3393: 3392: 3376: 3372: 3343: 3339: 3335: 3332: 3310: 3307: 3304: 3300: 3296: 3293: 3273: 3267: 3260: 3245: 3238: 3237: 3221: 3217: 3209: 3208: 3207: 3205: 3196: 3194: 3190: 3186: 3179: 3176: 3165: 3163: 3161: 3157: 3153: 3149: 3141: 3139: 3137: 3133: 3129: 3125: 3121: 3117: 3114: 3110: 3106: 3101: 3099: 3095: 3091: 3090:type-checking 3083: 3081: 3075: 3043: 3037: 3028: 3022: 3016: 3013: 3003: 2974: 2971: 2965: 2959: 2956: 2951: 2945: 2941: 2937: 2934: 2929: 2925: 2921: 2918: 2915: 2909: 2907: 2902: 2892: 2889: 2883: 2880: 2875: 2869: 2865: 2861: 2858: 2853: 2849: 2845: 2842: 2839: 2833: 2831: 2826: 2819: 2816: 2813: 2808: 2802: 2798: 2794: 2791: 2786: 2782: 2778: 2775: 2772: 2766: 2764: 2759: 2752: 2749: 2744: 2738: 2734: 2730: 2727: 2722: 2718: 2714: 2711: 2708: 2702: 2700: 2695: 2684: 2683: 2682: 2680: 2664: 2655: 2649: 2640: 2637: 2634: 2591: 2589: 2559: 2557: 2528: 2527: 2526: 2505: 2496: 2490: 2481: 2477: 2473: 2465: 2460: 2456: 2446: 2440: 2434: 2425: 2421: 2417: 2409: 2404: 2400: 2393: 2390: 2380: 2379: 2378: 2354: 2350: 2321: 2315: 2307: 2303: 2294: 2290: 2282: 2281: 2280: 2278: 2270: 2262: 2231: 2201: 2197: 2164: 2160: 2154: 2148: 2139: 2133: 2127: 2124: 2117: 2113: 2110: 2083: 2082: 2081: 2076: 2004: 1985: 1982: 1979: 1976: 1973: 1968: 1964: 1960: 1955: 1951: 1947: 1918: 1914: 1911: 1908: 1902: 1863: 1862: 1861: 1759: 1739: 1632: 1628: 1598: 1594: 1591: 1589: 1569: 1533: 1529: 1499: 1495: 1466: 1462: 1459: 1457: 1434: 1404: 1400: 1370: 1366: 1337: 1333: 1330: 1328: 1304: 1303: 1302: 1190: 1181: 1179: 1175: 1115: 1109: 1103: 1100: 1097: 1032: 1026: 1020: 1017: 1014: 1003: 984: 980: 974: 970: 966: 961: 957: 953: 949: 945: 939: 927: 913: 909: 903: 899: 895: 890: 886: 882: 878: 874: 868: 856: 855: 854: 852: 803: 801: 735: 734:type variable 719: 699: 693: 687: 684: 681: 624: 622: 608: 580: 560: 540: 537: 534: 505: 502: 499: 491: 486: 483: 480: 474: 466: 461: 456: 453: 442: 439: 405: 401: 397: 391: 386: 381: 378: 375: 367: 364: 361: 353: 348: 345: 331: 328: 322: 320: 318: 313: 311: 307: 303: 299: 295: 291: 287: 282: 268: 260: 244: 224: 196: 195:type variable 180: 157: 151: 148: 145: 139: 136: 133: 128: 124: 120: 117: 114: 108: 101: 100: 99: 97: 93: 89: 85: 80: 78: 75: 71: 68: 64: 60: 56: 52: 48: 44: 40: 36: 32: 28: 22: 21:Ferry Corsten 4037: 3991: 3971: 3957: 3943: 3923: 3886: 3880: 3861: 3855: 3815:. Retrieved 3813:. 2012-09-11 3805: 3794:. Retrieved 3792:. 2012-10-05 3789: 3780: 3769:. Retrieved 3765: 3756: 3748:the original 3727: 3723: 3713: 3698: 3680: 3659: 3651: 3639: 3635: 3629: 3588: 3553: 3552: 3471: 3467: 3461: 3454: 3363: 3197: 3188: 3181: 3175:Barendregt's 3172: 3159: 3155: 3151: 3145: 3102: 3087: 3001: 2999: 2623: 2520: 2337: 2277:constructors 2276: 2266: 2002: 2000: 1772:are of type 1689: 1182: 1001: 999: 804: 628: 526: 326: 323:Typing rules 316: 314: 283: 258: 172: 95: 91: 87: 81: 34: 30: 26: 25: 4106:Type theory 3615:Lambda cube 3178:lambda cube 3098:undecidable 2001:will do. A 553:are types, 306:lambda cube 292:. However, 261:is of type 72:(1972) and 4085:Categories 3912:References 3817:2019-09-23 3796:2019-09-23 3771:2019-07-08 3563:. System F 3455:That is, F 3120:Haskell 98 1816:IFTHENELSE 3790:ocaml.org 3561:subtyping 3530:λ 3510:Λ 3490:λ 3424:≤ 3417:⋃ 3407:ω 3377:ω 3336:∈ 3308:− 3297:∈ 3271:⇒ 3246:⋆ 3094:Joe Wells 3068:power of 3044:α 3041:→ 3038:α 3035:→ 3029:α 3026:→ 3023:α 3014:α 3011:∀ 2952:α 2949:→ 2946:α 2938:λ 2930:α 2922:λ 2916:α 2913:Λ 2876:α 2873:→ 2870:α 2862:λ 2854:α 2846:λ 2840:α 2837:Λ 2809:α 2806:→ 2803:α 2795:λ 2787:α 2779:λ 2773:α 2770:Λ 2745:α 2742:→ 2739:α 2731:λ 2723:α 2715:λ 2709:α 2706:Λ 2665:α 2662:→ 2656:α 2653:→ 2650:α 2644:→ 2641:α 2635:α 2632:∀ 2600:→ 2506:α 2503:→ 2497:α 2494:→ 2491:⋯ 2488:→ 2474:α 2450:→ 2447:⋯ 2441:α 2438:→ 2435:⋯ 2432:→ 2418:α 2391:α 2388:∀ 2319:→ 2316:⋯ 2313:→ 2300:→ 2198:λ 2155:α 2152:→ 2149:α 2146:→ 2140:α 2137:→ 2134:α 2125:α 2122:∀ 2114:λ 2003:predicate 1980:α 1969:α 1961:λ 1956:α 1948:λ 1915:λ 1909:α 1906:Λ 1595:λ 1496:λ 1463:λ 1367:λ 1334:λ 1264:→ 1236:→ 1191:λ 1116:α 1113:→ 1110:α 1107:→ 1104:α 1098:α 1095:∀ 1033:α 1030:→ 1027:α 1024:→ 1021:α 1015:α 1012:∀ 975:α 967:λ 962:α 954:λ 946:α 943:Λ 904:α 896:λ 891:α 883:λ 875:α 872:Λ 786:→ 720:α 700:α 697:→ 694:α 691:→ 688:α 682:α 679:∀ 609:α 581:α 561:α 541:τ 535:σ 506:σ 500:α 497:∀ 481:α 478:Λ 475:⊢ 472:Γ 467:σ 454:⊢ 443:α 437:Γ 406:α 398:τ 392:σ 382:τ 376:⊢ 373:Γ 368:σ 362:α 359:∀ 346:⊢ 343:Γ 269:α 245:α 225:λ 205:Λ 181:α 158:α 155:→ 152:α 146:α 143:∀ 129:α 121:λ 115:α 112:Λ 109:⊢ 4068:System F 3955:(1974). 3942:(1972), 3665:Harper R 3610:System U 3598:See also 3589:System F 3554:System F 3546:System F 3472:universe 3198:System F 3182:System F 3166:System F 3122:and the 3118:such as 712:, where 317:System F 82:Whereas 67:logician 27:System F 3840:(2005) 3642:: 160. 3187:or the 59:Haskell 37:) is a 4070:ω 4044:  4010:  3979:  3893:  3585:record 3391:to be 3286:where 2049:ISZERO 798:to be 584:  527:where 446:  173:where 29:(also 4116:Logic 3962:(PDF) 3690:(PDF) 3672:(PDF) 3621:Notes 3591:<: 3565:<: 3556:<: 3548:<: 3468:order 3204:kinds 3132:OCaml 3002:i.e., 1002:three 732:is a 284:As a 193:is a 88:types 4042:ISBN 4008:ISBN 3994:IEEE 3977:ISBN 3891:ISBN 3583:and 3325:and 3136:GADT 2377:as: 1150:and 827:and 629:The 588:type 521:(2) 450:type 424:(1) 61:and 4074:by 4000:doi 3928:doi 3866:doi 3732:doi 3644:doi 3128:GHC 1301:): 802:.) 53:in 33:or 4087:: 4036:. 4006:. 3847:, 3826:^ 3788:. 3764:. 3728:98 3726:. 3722:. 3667:. 3650:. 3640:45 3638:. 3594:. 3577:ML 3180:, 3162:. 3138:. 3124:ML 2910::= 2834::= 2767::= 2703::= 2080:: 853:: 312:. 94:→ 79:. 63:ML 4050:. 4016:. 4002:: 3985:. 3964:. 3948:. 3934:. 3930:: 3899:. 3874:. 3868:: 3820:. 3799:. 3774:. 3740:. 3734:: 3646:: 3476:ω 3464:ω 3457:ω 3438:i 3434:F 3427:i 3421:1 3412:= 3403:F 3373:F 3344:n 3340:F 3333:K 3311:1 3305:n 3301:F 3294:J 3274:K 3268:J 3222:n 3218:F 3200:ω 3184:ω 3168:ω 3078:f 3070:f 3066:n 3062:f 3058:n 3032:) 3020:( 3017:. 2981:) 2978:) 2975:x 2972:f 2969:( 2966:f 2963:( 2960:f 2957:. 2942:f 2935:. 2926:x 2919:. 2903:3 2896:) 2893:x 2890:f 2887:( 2884:f 2881:. 2866:f 2859:. 2850:x 2843:. 2827:2 2820:x 2817:f 2814:. 2799:f 2792:. 2783:x 2776:. 2760:1 2753:x 2750:. 2735:f 2728:. 2719:x 2712:. 2696:0 2659:) 2647:( 2638:. 2604:N 2596:N 2592:: 2583:c 2580:c 2577:u 2574:s 2564:N 2560:: 2551:o 2548:r 2545:e 2542:z 2523:N 2500:) 2485:] 2482:S 2478:/ 2471:[ 2466:m 2461:1 2457:K 2453:( 2444:) 2429:] 2426:S 2422:/ 2415:[ 2410:1 2405:1 2401:K 2397:( 2394:. 2375:S 2371:m 2355:i 2351:K 2340:S 2334:. 2322:S 2308:2 2304:K 2295:1 2291:K 2273:S 2246:T 2241:) 2237:F 2232:. 2225:n 2222:a 2219:e 2216:l 2213:o 2210:o 2207:B 2202:x 2195:( 2189:n 2186:a 2183:e 2180:l 2177:o 2174:o 2171:B 2165:n 2161:. 2143:) 2131:( 2128:. 2118:n 2111:= 2107:O 2104:R 2101:E 2098:Z 2095:S 2092:I 2078:0 2060:T 2033:n 2030:a 2027:e 2024:l 2021:o 2018:o 2015:B 1986:z 1983:y 1977:x 1974:. 1965:z 1952:y 1942:n 1939:a 1936:e 1933:l 1930:o 1927:o 1924:B 1919:x 1912:. 1903:= 1899:E 1896:S 1893:L 1890:E 1887:N 1884:E 1881:H 1878:T 1875:F 1872:I 1846:n 1843:a 1840:e 1837:l 1834:o 1831:o 1828:B 1800:n 1797:a 1794:e 1791:l 1788:o 1785:o 1782:B 1760:x 1740:x 1718:n 1715:a 1712:e 1709:l 1706:o 1703:o 1700:B 1670:T 1664:F 1657:n 1654:a 1651:e 1648:l 1645:o 1642:o 1639:B 1633:x 1629:. 1622:n 1619:a 1616:e 1613:l 1610:o 1607:o 1604:B 1599:x 1592:= 1584:T 1581:O 1578:N 1570:y 1565:T 1558:n 1555:a 1552:e 1549:l 1546:o 1543:o 1540:B 1534:x 1530:. 1523:n 1520:a 1517:e 1514:l 1511:o 1508:o 1505:B 1500:y 1490:n 1487:a 1484:e 1481:l 1478:o 1475:o 1472:B 1467:x 1460:= 1452:R 1449:O 1440:F 1435:y 1429:n 1426:a 1423:e 1420:l 1417:o 1414:o 1411:B 1405:x 1401:. 1394:n 1391:a 1388:e 1385:l 1382:o 1379:o 1376:B 1371:y 1361:n 1358:a 1355:e 1352:l 1349:o 1346:o 1343:B 1338:x 1331:= 1323:D 1320:N 1317:A 1287:n 1284:a 1281:e 1278:l 1275:o 1272:o 1269:B 1259:n 1256:a 1253:e 1250:l 1247:o 1244:o 1241:B 1231:n 1228:a 1225:e 1222:l 1219:o 1216:o 1213:B 1159:F 1137:T 1101:. 1073:n 1070:a 1067:e 1064:l 1061:o 1058:o 1055:B 1018:. 985:y 981:. 971:y 958:x 950:. 940:= 936:F 914:x 910:. 900:y 887:x 879:. 869:= 865:T 836:F 814:T 764:n 761:a 758:e 755:l 752:o 749:o 746:B 685:. 657:n 654:a 651:e 648:l 645:o 642:o 639:B 538:, 503:. 492:: 487:M 484:. 462:: 457:M 440:, 409:] 402:/ 395:[ 387:: 379:M 365:. 354:: 349:M 259:x 149:. 140:: 137:x 134:. 125:x 118:. 96:A 92:A 23:.

Index

Ferry Corsten
typed lambda calculus
simply typed lambda calculus
universal quantification
parametric polymorphism
programming languages
Haskell
ML
logician
Jean-Yves Girard
computer scientist
John C. Reynolds
simply typed lambda calculus
type variable
term rewriting system
strongly normalizing
type inference
Curry–Howard isomorphism
intuitionistic logic
lambda cube
dependent types
type variable
right-associative
Church booleans
Bourbaki sense
fixed-point combinator
Church numeral
Martin-Löf's type theory
Church numerals
higher-order function

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