Difference between revisions of "VTLUUG:2016-03-24"
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Lambda Calculus forms the fundamentals of functional programming. If it can be described as a function, | Lambda Calculus forms the fundamentals of functional programming. If it can be described as a function, | ||
it can be described in the lambda calculus and consequently written in Haskell | it can be described in the lambda calculus and consequently written in Haskell | ||
| + | |||
| + | [https://linx.vtluug.org/selif/97s2gvcx.pdf Slides] | ||
=== Alpha equivalence === | === Alpha equivalence === | ||
| Line 48: | Line 50: | ||
Meat of Lambda calculus. | Meat of Lambda calculus. | ||
| − | + | === Currying === | |
| + | Allows for nested functions. Functions manipulate each input individually | ||
| + | |||
| + | ===Examples=== | ||
<pre> | <pre> | ||
| − | (ƛx.x)2 | + | |
| − | (ƛ[x:= | + | (ƛx.x)2 |
| − | + | (ƛ[x:=2]) x is bound to 2 | |
| + | 2 | ||
| + | </pre> | ||
| + | <pre> | ||
(ƛz.zz)(ƛy.yy) | (ƛz.zz)(ƛy.yy) | ||
| − | (ƛ[z:=( | + | (ƛ[z:=(ƛy.yy)].zz) |
| + | (ƛy.yy)(ƛy.yy) | ||
| + | (ƛy.yy) | ||
| + | 1 | ||
</pre> | </pre> | ||
| − | + | <pre> | |
| + | |||
| + | Currying example: | ||
| + | |||
| + | (ƛabc.cba)zz(ƛwv.w) | ||
| + | (ƛa.(ƛb.(ƛc.cba)))(z)z(ƛw.(ƛv.w))) The first function only applies the first z | ||
| + | (ƛb.(ƛc.cbz))z(ƛw.(ƛv.w)) Applies from the outer parenthesis in | ||
| + | (ƛc.czz)(ƛw.(ƛv.w)) So c is applied last | ||
| + | (ƛw.(ƛv.w))zz | ||
| + | (ƛv.z)z | ||
| + | z | ||
| + | |||
| + | </pre> | ||
| + | <pre> | ||
| + | |||
| + | (ƛx.ƛy.xyy)(ƛa.a)b | ||
| + | (ƛy.(ƛa.a)yy)(b) | ||
| + | (ƛa.a)bb | ||
| + | bb | ||
| + | </pre> | ||
| + | <pre> | ||
| + | (ƛx.x)(ƛy.yy)(ƛz.zq) (ƛx.x) is the identity | ||
| + | (ƛy.yy)(ƛz.zq) | ||
| + | (ƛz.zq)(ƛz.zq) | ||
| + | qq | ||
| + | </pre> | ||
[[Category:VTLUUG:Meetings]] | [[Category:VTLUUG:Meetings]] | ||
[[Category:2016]] | [[Category:2016]] | ||
Latest revision as of 07:18, 3 January 2018
Our seventh meeting of the 2016 Spring semester, and Officer Elections
Contents
Date, Time, and Location
- Thursday, 24 March
- 8:30pm - 10:30pm
- 1040 Torgersen Hall
Announcements
- #VTLUUG: "No Rules, Just Right™"
- 2016 is the year of the Linux desktop
- For shell account, contact uncurlhalo
- Interest gauge for SouthEast LinuxFest 2016
Curriculum du jour
- Officer Elections
- This is a consequence of new club registration policies.
Results
- President
- Jacob Melton
- VP of not IT
- Marcus Wanners
- Secretary/Treasurer
- John Volk
Talks
- ackthet is giving the talk: Lambda Calculus for Babies. Retarded Babies.
- First in ackthet's 10-part talk on Xmonad, starting from the basics of haskell
Hacking
- Gobblerpedia
- VTLUUG Wiki
- Wiki meeting page creation script -- this needs to happen so echarlie isn't doing it manually
- New Website?
- Infrastructure 2016
Lambda Calculus for Babies: Retarded Babies
Lambda Calculus forms the fundamentals of functional programming. If it can be described as a function, it can be described in the lambda calculus and consequently written in Haskell
Alpha equivalence
- Variable name doesn't matter
Beta reduction
Meat of Lambda calculus.
Currying
Allows for nested functions. Functions manipulate each input individually
Examples
(ƛx.x)2 (ƛ[x:=2]) x is bound to 2 2
(ƛz.zz)(ƛy.yy) (ƛ[z:=(ƛy.yy)].zz) (ƛy.yy)(ƛy.yy) (ƛy.yy) 1
Currying example: (ƛabc.cba)zz(ƛwv.w) (ƛa.(ƛb.(ƛc.cba)))(z)z(ƛw.(ƛv.w))) The first function only applies the first z (ƛb.(ƛc.cbz))z(ƛw.(ƛv.w)) Applies from the outer parenthesis in (ƛc.czz)(ƛw.(ƛv.w)) So c is applied last (ƛw.(ƛv.w))zz (ƛv.z)z z
(ƛx.ƛy.xyy)(ƛa.a)b (ƛy.(ƛa.a)yy)(b) (ƛa.a)bb bb
(ƛx.x)(ƛy.yy)(ƛz.zq) (ƛx.x) is the identity (ƛy.yy)(ƛz.zq) (ƛz.zq)(ƛz.zq) qq
