Why Elm

Transcript

1. W hat is E lm? L angu age (and "fr amew or k") for bu ilding w eb fr ont end app licat ions C an be us ed in p lace of HTML , CSS and J av a S cr ipt C omp iles int o t he abov e
2. W hy choose E lm?
3. T he problem with J ava S cript F ew p eop le know all of J av a S cr ipt ‑ in fact it is gett ing mor e and mor e comp lex each y ear. B ad featur es ar e nev er r emov ed, just lint ed D iffer ent p eop le hav e v ery differ ent w ays of us ing t he langu age (object‑or ient ed, fu nct ional, t his‑less, ...)
4. T he problem with J ava S cript (cont.) W it h J av a S cr ipt, anyt hing may su ddenly fail in pr odu ct ion becaus e of an ov ers ight N ot hing can s av e y ou fr om t hat (ex cept may be boat loads of menial t ests: w hat if t his fu nct ion is called w it hout ar gu ments, w it h an empty arr ay...) I t t akes a gr eat deal of dis cip line t o keep code r eadable and adher e t o t he pr oject's code sty le
5. T he problem with J ava S cript (cont.) H u ge p ot ent ial for r egr ess ions w hen r efact or ing E v ery pr oject has a w ildly differ ent bu ild s cheme s ince t her e is no "official" or ev en gener ally s ett led‑up on t oolchain I t is common for bu ilds t o br eak becaus e a libr ary w as up dat ed
6. J ava S cript is unwieldy in big projects J ava S cript is in fact poorly suited for lean development, because refactoring is risky
7. H ow E lm solves it E lm is a s imp le and comp act langu age I t does not hav e t he baggage of J av a S cr ipt's hist ory P ast r eleas es hav e made it s imp ler and s imp ler ‑ t he maint ainers cont inu e t o r emov e confus ing langu age featur es
8. H ow E lm solves it (cont.) I t has a gr eat typ e syst em t hat helps model dat a and app licat ion st at es T his can be us ed t o eliminat e an ent ir e cat egory of bu gs: arr iv ing in imp oss ible st at es I f t he code comp iles, it is corr ect (can st ill hav e logic err ors, of cours e)
9. H ow E lm solves it (cont.) E lm has no n u l l or u n d e f i n e d E lm has no ru nt ime ex cept ions ex cept for D e b u g . c r a s h A ll p ot ent ial cas es need t o be handled ‑ no surpr is es or u nhandled err ors, gu ar ant eed! U s ing T yp e S cr ipt or F low can giv e s ome of t he benefits, but many libr ar ies' typ ings w ill st ill non‑ex haust iv e)
10. H ow E lm solves it (cont.) E lm enfor ces wr it ing code in a s ingle p ar adigm and sty le (fu nct ional, no mut able st at e) I t comes w it h gr eat t ooling out of t he box B u ilds can nev er br eak becaus e of libr ary up dat es, becaus e s emant ic v ers ioning is ensur ed by t he p ackage manager
11. E lm is very well suited for lean development, because refactoring E lm is fun and we can do it with confidence!
12. B ut a new language, surely it's an additional cost! J av a S cr ipt pr ojects us e a combinat ion of e.g. R eact, R edux, r edux‑loop, et c. T hey might ev en be us ing T yp e S cr ipt or F low, w hich ar e langu ages w it h gr eat impr ov ements ov er p lain JS B ut t hey bu ild on t op of JS , and as s aid befor e, few know t he w hole decor at ed p ast of J av a S cr ipt
13. B ut a new language, surely it's an additional cost! T her e is v ery likely no ot her Zendes k pr oject w it h t he ex act s ame libr ar ies and/or code sty le N ew dev in a JS pr oject needs at least a w eek or tw o t o lear n t he pr oject E lm is a s mall langu age I t t akes a coup le of w eeks t o be pr odu ct iv e A bout a mont h or tw o t o mast er all of it T he E lm comp iler is t he st at e of t he art w hen it comes t o fr iendly err or mess ages
14. B ut a new language, surely it's an additional cost! A ll E lm pr ojects follow t he s ame gener al p att er n, becaus e t he langu age does n't allow anyt hing els e E lm code is easy t o r ead as it commu nicat es int ent ions w ell N ew dev can't inadv ert ent ly mess up an E lm pr oject
15. W hat if the language development is discontinued in a year E v en if t he langu age dev elop ment w as dis cont inu ed t oday, it w ou ld be fine T her e's no r eas on w hy a pr oject cou ldn't be us ing an older v ers ion of E lm for y ears t o come JS as a comp ile t ar get is s olid, becaus e all old JS code w ill cont inu e t o w or k in br ows ers als o in t he futur e. (O ne J av a S cr ipt (1JS ) pr incip le)
16. W hen to choose E lm and when not to
17. W hat is E lm a poor fit for M ost ly st at ic p ages (e.g. news w ebs it es) V ery s hort pr ojects w her e y ou actu ally w ant t o us e r eady‑made UI comp onents (e.g. MVP admin UI s) L ots of int egr at ion w it h t err ible t hir d‑p arty J av a S cr ipt (adv ert is ements in p art icu lar) S it es t hat need s erv er‑s ide r ender ing A ls o w ort h r emember ing, it can't be us ed t o bu ild a backend
18. W hat is E lm great for S ingle p age app licat ions B esp oke des ign L onger pr oject (> 2 mont hs) E sp ecially help fu l for bigger fr ont end t eams
19. J avascript E lm V iew R eact L angu age S t at e M anagement R edux, M obx, B aobab, ... L angu age I mmut ability I mmut able, s eamless‑immut able L angu age R out ing R eact‑R out er L angu age B u ild T ool W ebp ack L angu age R emot e D at a P r omis es, R x L angu age P ackage M anagement np m/y ar n L angu age S ty ling CSS M odu les, SASS , S ty led C omp onents, et c elm‑css, any T est ing M ocha, J as mine, J est, E nzy me, C apy bar a elm‑t est
20. J avascript E lm G r ap h QL R elay elm‑gr ap hq l A nimat ion R eact‑M ot ion elm‑sty le‑animat ion A ut o‑F or matt ing N one elm‑for mat W eb comp onents ✓ ✓ A dv anced E dit or S upp ort ✓ A ut omat ic V ers ion U p gr ade ✓
21. P r os: 1. N o ru nt ime err ors 2. E xtr emely easy r efact or ing 3. H igh qu ality libr ar ies 4. O bv ious naming for dis cov er ability and collabor at ion 5. E asy t o lear n w/ incr edible err or mess ages 6. E asy/aut omat ed up gr ades 7. C an alw ays eas ily int er op w it h JS /E mber/R eact/et c 8. S ame ar chit ectur e for ev ery app (game/w ebs it e/SPA /et c) 9. M akes dev elop ment fu n
22. C ons: 1. N ot near ly as many t hir d‑p arty libr ar ies 2. A ss et M anagement, next r eleas e 3. S erv er S ide r ender ing, next r eleas e 4. R u nt ime bu ndle w ill not be as s mall as S v elt e 5. S t ill exp er iment al on mobile 6. C annot s har e code on t he s erv er for at least anot her y ear
23. I hav e been wr it ing E lm for 1.5 y ears nev er a need t o ju mp int o a JS debu gger. hav e been able t o wr it e JS & E lm w/o issu es hav e put E lm int o R eact apps w/ > 5k lines of app code fellow class mat es able t o be pr odu ct iv e w it hin a w eek bu ilt & bu ilding elm‑aut ocomp let e, elm‑calendar, elm‑ r eor der able st ill a "fu nct ional pr ogr amming" beginner. I don't wr it e H as kell. E lm is pr agmat ic